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Sample records for semiconductor lasers based

  1. Ring resonator based narrow-linewidth semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander (Inventor)

    2005-01-01

    The present invention is a method and apparatus for using ring resonators to produce narrow linewidth hybrid semiconductor lasers. According to one embodiment of the present invention, the narrow linewidths are produced by combining the semiconductor gain chip with a narrow pass band external feedback element. The semi conductor laser is produced using a ring resonator which, combined with a Bragg grating, acts as the external feedback element. According to another embodiment of the present invention, the proposed integrated optics ring resonator is based on plasma enhanced chemical vapor deposition (PECVD) SiO.sub.2 /SiON/SiO.sub.2 waveguide technology.

  2. Laser apparatus for surgery and force therapy based on high-power semiconductor and fibre lasers

    SciTech Connect

    Minaev, V P

    2005-11-30

    High-power semiconductor lasers and diode-pumped lasers are considered whose development qualitatively improved the characteristics of laser apparatus for surgery and force therapy, extended the scope of their applications in clinical practice, and enhanced the efficiency of medical treatment based on the use of these lasers. The characteristics of domestic apparatus are presented and their properties related to the laser emission wavelength used in them are discussed. Examples of modern medical technologies based on these lasers are considered. (invited paper)

  3. Refractive index sensing based on semiconductor nanowire lasers

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoqin; Chen, Qiushu; Xu, Peizhen; Tong, Limin; Fan, Xudong

    2017-07-01

    We demonstrate a refractive index (RI) sensor based on semiconductor nanowire lasers. It is shown that the TE01 mode is responsible for lasing and sensing with the lasing threshold of 3 μJ/mm2 and the lasing peak width as narrow as 0.22 nm. A RI sensitivity of 21.2 nm/RIU (refractive index units), a figure of merit of approximately 100, and an RI detection limit of 1.4 ×10-3 RIU are achieved.

  4. Compact self-contained blood coagulator based on semiconductor laser

    NASA Astrophysics Data System (ADS)

    Svirin, Vaytcheslav N.; Rogatkin, Dmitrii A.; Chernenko, P.

    2001-01-01

    In recent years significant improvement of power and spectral characteristics of semiconductor lasers has taken place. The power of serial single near-IR semiconductor lasers has achieved units of watts, the spectral range has been extended from 0.63 to 1.7...1.8 micrometers . The available level of semiconductor lasers, their small dimensions and weight, together with the characteristics of the modern fiberoptic systems, electronic and microprocessor components as well as small dimensions and weight of modern power supplies allow development of a compact portable self-contained blood coagulator, which is of great importance for use in various emergencies, natural calamities, and in many other areas. The report discusses the problems of designing the coagulator, its technical and user characteristics as well as the possibilities to use such a coagulator in other fields of laser medicine.

  5. A design of atmospheric laser communication system based on semiconductor laser

    NASA Astrophysics Data System (ADS)

    Rao, Jionghui; Yao, Wenming; Wen, Linqiang

    2016-01-01

    This paper uses semiconductor laser with 905nm wave length as light source to design a set of short-distance atmospheric laser communication system. This system consists of laser light source, launch modulation circuit, detector, receiving and amplifying circuit and so on. First, this paper analyzes the factors which lead to the decrease of luminous power of laser communication link under the applicable environment-specific sea level, then this paper elicits the relationship of luminous power of receiving optical systems and distance, slant angle and divergence angle which departures from the laser beam axis by using gaussian beam geometric attenuation mode. Based on the two reasons that PPM modulation theory limits the transmission rate of PPM modulation, that is, this paper makes an analysis on repetition frequency and pulse width of laser, makes theoretical calculation for typical parameters of semiconductor laser and gets the repetition frequency which is 10KHz, pulse width is50ns, the transmission rate is 71.66 Kb/s, at this time, modulation digit is 9; then this paper selects frame synchronization code of PPM modulation and provides implementation method for test; lastly, programs language based on Verilog, uses the FPGA development board to realize PPM modulation code and does simulation test and hardware test. This paper uses APD as the detector of receiving and amplifying circuit. Then this paper designs optical receiving circuit such as amplifying circuit, analog-digital conversion circuit based on the characteristics of receipt.

  6. Web-based interactive educational software introducing semiconductor laser dynamics: Sound of Lasers (SOL)

    NASA Astrophysics Data System (ADS)

    Consoli, Antonio; Sanchez, Jorge R.; Horche, Paloma R.; Esquivias, Ignacio

    2014-07-01

    presented. The proposed tool is addressed to the students of optical communication courses, encouraging self consolidation of the subjects learned in lectures. The semiconductor laser model is based on the well known rate equations for the carrier density, photon density and optical phase. The direct modulation of the laser is considered with input parameters which can be selected by the user. Different options for the waveform, amplitude and frequency of the injected current are available, together with the bias point. Simulation results are plotted for carrier density and output power versus time. Instantaneous frequency variations of the laser output are numerically shifted to the audible frequency range and sent to the computer loudspeakers. This results in an intuitive description of the "chirp" phenomenon due to amplitude-phase coupling, typical of directly modulated semiconductor lasers. In this way, the student can actually listen to the time resolved spectral content of the laser output. By changing the laser parameters and/or the modulation parameters, consequent variation of the laser output can be appreciated in intuitive manner. The proposed educational tool has been previously implemented by the same authors with locally executable software. In the present manuscript, we extend our previous work to a web based platform, offering improved distribution and allowing its use to the wide audience of the web.

  7. Semiconductor microcavity lasers

    SciTech Connect

    Gourley, P.L.; Wendt, J.R.; Vawter, G.A.; Warren, M.E.; Brennan, T.M.; Hammons, B.E.

    1994-02-01

    New kinds of semiconductor microcavity lasers are being created by modern semiconductor technologies like molecular beam epitaxy and electron beam lithography. These new microcavities exploit 3-dimensional architectures possible with epitaxial layering and surface patterning. The physical properties of these microcavities are intimately related to the geometry imposed on the semiconductor materials. Among these microcavities are surface-emitting structures which have many useful properties for commercial purposes. This paper reviews the basic physics of these microstructured lasers.

  8. Slow Light Semiconductor Laser

    DTIC Science & Technology

    2015-02-02

    we demonstrate a semiconductor laser with a spectral linewidth of 18 kHz in the telecom band around 1:55um. The views, opinions and/or findings...we demonstrate a semiconductor laser with a spectral linewidth of 18 kHz in the telecom band around 1:55um. Further, the large intracavity field...hybrid Si/III- V platforms Abstract The semiconductor laser is the principal light source powering the world-wide optical fiber network . Ever

  9. Subpicosecond Carrier Dynamics in Semiconductor Lasers and Lasers Based on Intersubband Transition.

    NASA Astrophysics Data System (ADS)

    Sung, Chun-Yung

    intersubband relaxation in stepped quantum well structures for far-infrared lasers were also measured. We have obtained quite good agreement between theoretical and experimental values for the intersubband relaxation rates in undoped structures. It is shown that the modified intersubband relaxation rates in the stepped quantum well allow us to establish a population inversion between subbands in both the proposed optically pumped and electrically pumped FIR semiconductor laser structures. When the n=3 state is pumped, a population inversion between n3 and n2 (separated by 7 THz) is observed, which will be appropriate for an optically-pumped FIR laser. Low-temperature-grown GaAs (LT-GaAs) is very important for many high speed optoelectronic application. Previous experiments have indicated the role of both EL2-like arsenic anti-site defect centers or arsenic precipitates in producing an ultrafast lifetime. We have performed a multi-wavelength pump-probe experiment to probe the separate electron and hole capture times. Using high carrier density excitation to saturate the midgap traps, we have determined the carrier life time in the defect band. A better understanding of the dynamics of electrons and holes in LT-GaAs will lead to optimization of electronic and photoconductive devices based on these materials.

  10. Widely tunable lasers based on mode-hop-free semiconductor laser array

    NASA Astrophysics Data System (ADS)

    Kurobe, T.; Kimoto, T.; Muranushi, K.; Mukaihara, T.; Ariga, M.; Kagimoto, T.; Kagi, N.; Matsuo, N.; Kasukawa, A.

    2007-11-01

    Integration of mode-hop-free tunable laser array and a semiconductor optical amplifier is most reliable approach to realize widely tunable lasers. We have developed two types of tunable lasers, one is a thermally tunable DFB laser array for DWDM tunable transponders, which has shown high power and wide tunability covering Cband or L-band, housing in compact butterfly packages with robust wavelength locker. Another is a short-cavity DBR laser array for optical burst switching, whose lasing frequency can be monotonously tuned and locked on the ITU grid within 5 microseconds. Both lasers have demonstrated superior performances in system experiments.

  11. Tunable semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

    2006-01-01

    Tunable semiconductor lasers are disclosed requiring minimized coupling regions. Multiple laser embodiments employ ring resonators or ring resonator pairs using only a single coupling region with the gain medium are detailed. Tuning can be performed by changing the phase of the coupling coefficient between the gain medium and a ring resonator of the laser. Another embodiment provides a tunable laser including two Mach-Zehnder interferometers in series and a reflector coupled to a gain medium.

  12. Investigation of laser radar systems based on mid-infrared semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Rybaltowski, Adam

    This dissertation deals with the possibility of utilizing mid-infrared semiconductor lasers in systems of optical remote sensing with range resolution, called laser radar or lidar. The main subject investigated in this dissertation is two-fold: firstly, an analysis of the signal-to-noise ratio (SNR) and related maximum sensing range calculations in this type of lidar based on available system components, and---secondly---improvements in the Random-Modulation Continuous-Wave (RM-CW) lidar technique to better utilize available mid-infrared semiconductor lasers. As far as the SNR analysis is concerned, an appropriate framework has been constructed to analyze post-demodulation noise in mid-infrared direct-detection RM-CW lidar. It is based on a generalization of the Wiener-Khintchine theorem; noise is assumed to be additive, stationary, and have an arbitrary power spectrum. This is in contrast to the SNR analysis in the literature on this subject, which is inadequate for mid-infrared RM-CW lidar as it only considers Poissonian fluctuations of the number of detected photons. In addition to regular SNR analysis, the framework derived in this dissertation allows treatment of singularities such as demodulation with an unbalanced sequence in 1/f noise. To calculate maximum lidar sensing range, the following detection limits have been considered: signal shot noise, background blackbody radiation shot noise based on the Background-Limited Photodetection (BLIP) detectivity limit, and minimum-size detector noise given by diffraction-limited focusing. The latter is found to be of greatest practical interest. Furthermore, a lidar figure of merit has been introduced, and all quantities related to lidar performance and its detection limits have been presented graphically. Since pseudo-random sequences discussed in the literature have been found highly non-optimal for most applications of RM-CW lidar, a framework for the construction of new pseudo-random sequences of desired

  13. Study on optical frequency domain reflectometry based on tunable semiconductor laser

    NASA Astrophysics Data System (ADS)

    Li, Guoyu; Liu, Tongqing; Zhang, Liwei; Guan, Bai-ou

    2009-11-01

    The relation of beat frequency, sweep rate, optical frequency modulation excursion and length of fiber under test (FUT) based on tunable semiconductor laser is studied. Experimental results show that the frequency of beat signal will increase when the length of the FUT, optical frequency modulation excursion or sweep rate increases.

  14. Semiconductor nanowire lasers

    NASA Astrophysics Data System (ADS)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong

    2016-06-01

    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  15. Semiconductor laser-based ranging instrument for earth gravity measurements

    NASA Technical Reports Server (NTRS)

    Abshire, James B.; Millar, Pamela S.; Sun, Xiaoli

    1995-01-01

    A laser ranging instrument is being developed to measure the spatial variations in the Earth's gravity field. It will range in space to a cube corner on a passive co-orbiting sub-satellite with a velocity accuracy of 20 to 50 microns/sec by using AlGaAs lasers intensity modulated at 2 GHz.

  16. Laser beam shaping optical system design methods and their application in edge-emitting semiconductor laser-based LIDAR systems

    NASA Astrophysics Data System (ADS)

    Serkan, Mert

    LIDAR (Light Detection And Ranging) systems are employed for numerous applications such as remote sensing, military applications, optical data storage, display technology, and material processing. Furthermore, they are superior to other active remote sensing tools such as RADAR systems, considering their higher accuracy and more precise resolution due to their much shorter wavelengths and narrower beamwidth. Several types of lasers can be utilized as the radiation source of several LIDAR systems. Semiconductor laser-based LIDAR systems have several advantages such as low cost, compactness, broad range of wavelengths, and high PRFs (Pulse Repetition Frequency). However, semiconductor lasers have different origins and angles of divergence in the two transverse directions, resulting in the inherent astigmatism and elliptical beam shape. Specifically, elliptical beam shape is not desirable for several laser-based applications including LIDAR systems specifically designed to operate in the far-field region. In this dissertation, two mirror-based and two lens-based beam shapers are designed to circularize, collimate, and expand an edge-emitting semiconductor laser beam to a desired beam diameter for possible application in LIDAR systems. Additionally, most laser beams including semiconductor laser beams have Gaussian irradiance distribution. For applications that require uniform illumination of an extended target area, Gaussian irradiance distribution is undesirable. Therefore, a specific beam shaper is designed to transform the irradiance distribution from Gaussian to uniform in addition to circularizing, collimating, and expanding the semiconductor laser beam. For the design of beam shapers, aperture sizes of the surfaces are preset for desired power transmission and allowed diffraction level, surface parameters of the optical components and the distances between these surfaces are determined. Design equations specific to these beam shaping optical systems are

  17. Diode-Laser Pumped Far-Infrared Local Oscillator Based on Semiconductor Quantum Wells

    NASA Technical Reports Server (NTRS)

    Kolokolov, K.; Li, J.; Ning, C. Z.; Larrabee, D. C.; Tang, J.; Khodaparast, G.; Kono, J.; Sasa, S.; Inoue, M.; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    The contents include: 1) Tetrahertz Field: A Technology Gap; 2) Existing THZ Sources and Shortcomings; 3) Applications of A THZ Laser; 4) Previous Optical Pumped LW Generations; 5) Optically Pumped Sb based Intersubband Generation Whys; 6) InGaAs/InP/AlAsSb QWs; 7) Raman Enhanced Optical Gain; 8) Pump Intensity Dependence of THZ Gain; 9) Pump-Probe Interaction Induced Raman Shift; 10) THZ Laser Gain in InGaAs/InP/AlAsSb QWs; 11) Diode-Laser Pumped Difference Frequency Generation (InGaAs/InP/AlAsSb QWs); 12) 6.1 Angstrom Semiconductor Quantum Wells; 13) InAs/GaSb/AlSb Nanostructures; 14) InAs/AlSb Double QWs: DFG Scheme; 15) Sb-Based Triple QWs: Laser Scheme; and 16) Exciton State Pumped THZ Generation. This paper is presented in viewgraph form.

  18. Low-noise III-V metasurface based semiconductor vortex laser and rotational Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Seghilani, Mohamed; Chomet, Baptiste; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Beaudoin, Gregoire; Sagnes, Isabelle; Lalanne, Philippe; Garnache, Arnaud

    2017-03-01

    We demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis.24 We use a first order phase perturbation to introduce a weak orbital anisotropy, based on a dielectric metasurface and non-linear laser dynamics, allowing selecting vortex handedness. Moreover, similarly to linear Doppler Shift, light carrying orbital angular momentum L, scattered by a rotating object at angular velocity, experiences a rotational Doppler shift L. We show that this fundamental light matter interaction can be detected exploiting self-mixing in a vortex laser under Doppler-shifted optical feedback, with quantum noise-limited light detection.25 This will allow us to combine a velocity sensor with optical tweezers for micro-manipulation applications, with high performances, simplicity and compactness. Such high performance laser opens the path to widespread new photonic applications.

  19. Fibre ring cavity semiconductor laser

    SciTech Connect

    Duraev, V P; Medvedev, S V

    2013-10-31

    This paper presents a study of semiconductor lasers having a polarisation maintaining fibre ring cavity. We examine the operating principle and report main characteristics of a semiconductor ring laser, in particular in single- and multiple-frequency regimes, and discuss its application areas. (lasers)

  20. Frequency tunable optoelectronic oscillator based on a directly modulated DFB semiconductor laser under optical injection.

    PubMed

    Wang, Peng; Xiong, Jintian; Zhang, Tingting; Chen, Dalei; Xiang, Peng; Zheng, Jilin; Zhang, Yunshan; Li, Ruoming; Huang, Long; Pu, Tao; Chen, Xiangfei

    2015-08-10

    A frequency tunable optoelectronic oscillator based on a directly modulated distributed-feedback (DFB) semiconductor laser under optical injection is proposed and experimentally demonstrated. Through optical injection, the relaxation oscillation frequency of the DFB laser is enhanced and its high modulation efficiency can enable the loop oscillation with a RF threshold gain of less than 20 dB. The DFB laser is a commercial semiconductor laser with a package of 10 GHz, and its packaging limitation can be overcome by optical injection. In our scheme, neither a high-speed external modulator nor an electrical bandpass filter is required, making the system simple and low-cost. Microwave signals with a frequency tuning range from 5.98 to 15.22 GHz are generated by adjusting the injection ratio and frequency detuning between the master and slave lasers. The phase noise of the generated 9.75 GHz microwave signal is measured to be -104.8 dBc/Hz @ 10 kHz frequency offset.

  1. Chaotic communication in radio-over-fiber transmission based on optoelectronic feedback semiconductor lasers.

    PubMed

    Lin, Fan-Yi; Tsai, Meng-Chiao

    2007-01-22

    Performance of chaotic communication in radio-over-fiber (ROF) transmission based on optoelectronic feedback semiconductor lasers is studied numerically. The chaotic carrier is generated by optoelectronic feedback semiconductor lasers, where chaotic communication is realized by synchronizing a receiver laser with a transmitter laser. Transmission quality of different message encoding schemes, including additive chaos modulation (ACM) and on-off shift keying (OOSK), are investigated and compared. In this study, the dispersion and nonlinearity effects in the fiber transmission module and the amplified spontaneous emission noise from the optical amplifiers are considered. In the wireless channel, effects of additive white Gaussian noise, multipath, and path loss are included. To quantitatively study the performance of this chaotic communication system in the ROF transmission, bit-error-rates (BER) of different transmission lengths, message bit-rates, and signal-to-noise ratios are studied. The optimal launched power and message strength that minimize the BER while assuring effective communication security are discussed. While the ACM scheme is shown to perform better in a fiber only configuration, the OOSK scheme shows better immunity to the random effects and waveform distortions presented in the wireless channel.

  2. Simple and compact tunable semiconductor lasers based on novel half-wave coupler

    NASA Astrophysics Data System (ADS)

    He, Jian-Jun; Xiong, Xiaohai; Meng, Jianjun; Wu, Lin; Zhang, Sen; Liao, Xiaolu; Zou, Li

    2015-02-01

    Widely tunable semiconductor lasers based on a novel half-wave coupler are presented. They have been implemented in the form of half-wave coupled V-cavity and ring-FP cavities. By using the novel half-wave coupler, single-mode lasing with high side-mode-suppression-ratio is achieved. Single-electrode controlled wide-band wavelength tuning with Vernier effect is demonstrated. The full-band tuning of 50 channels with 100GHz spacing is realized by further employing temperature induced gain spectrum shift. The laser is packaged into a small-form-factor 9-pin box TOSA, and the electronic driver has been developed for the wavelength tuning and direct modulation. The advantages of compactness, fabrication simplicity, easy wavelength control and direct modulation allow the tunable lasers to be used in low-cost access and datacenter networks, as well as in portable devices for spectroscopic analysis.

  3. Influences of semiconductor laser on fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Liang, Sheng; Zhang, Chun-Xi; Lin, Bo; Lin, Wen-Tai; Li, Qin; Zhong, Xiang; Li, Li-Jing

    2010-12-01

    This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.

  4. Semiconductor Laser Low Frequency Noise Characterization

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Logan, Ronald T.

    1996-01-01

    This work summarizes the efforts in identifying the fundamental noise limit in semiconductor optical sources (lasers) to determine the source of 1/F noise and it's associated behavior. In addition, the study also addresses the effects of this 1/F noise on RF phased arrays. The study showed that the 1/F noise in semiconductor lasers has an ultimate physical limit based upon similar factors to fundamental noise generated in other semiconductor and solid state devices. The study also showed that both additive and multiplicative noise can be a significant detriment to the performance of RF phased arrays especially in regard to very low sidelobe performance and ultimate beam steering accuracy. The final result is that a noise power related term must be included in a complete analysis of the noise spectrum of any semiconductor device including semiconductor lasers.

  5. GaN nanostructure-based light emitting diodes and semiconductor lasers.

    PubMed

    Viswanath, Annamraju Kasi

    2014-02-01

    GaN and related materials have received a lot of attention because of their applications in a number of semiconductor devices such as LEDs, laser diodes, field effect transistors, photodetectors etc. An introduction to optical phenomena in semiconductors, light emission in p-n junctions, evolution of LED technology, bandgaps of various semiconductors that are suitable for the development of LEDs are discussed first. The detailed discussion on photoluminescence of GaN nanostructures is made, since this is crucial to develop optical devices. Fabrication technology of many nanostructures of GaN such as nanowires, nanorods, nanodots, nanoparticles, nanofilms and their luminescence properties are given. Then the optical processes including ultrafast phenomena, radiative, non-radiative recombination, quantum efficiency, lifetimes of excitons in InGaN quantum well are described. The LED structures based on InGaN that give various important colors of red, blue, green, and their design considerations to optimize the output were highlighted. The recent efforts in GaN technology are updated. Finally the present challenges and future directions in this field are also pointed out.

  6. Silicon photonics WDM interconnects based on resonant ring modulators and semiconductor mode locked laser

    NASA Astrophysics Data System (ADS)

    Müller, J.; Hauck, J.; Shen, B.; Romero-García, S.; Islamova, E.; Sharif Azadeh, S.; Joshi, S.; Chimot, N.; Moscoso-Mártir, A.; Merget, F.; Lelarge, F.; Witzens, J.

    2015-03-01

    We demonstrate wavelength domain multiplexed (WDM) data transmission with a data rate of 14 Gbps based on optical carrier generation with a single-section semiconductor mode-locked laser (SS-MLL) and modulation with a Silicon Photonics (SiP) resonant ring modulator (RRM). 18 channels are sequentially measured, whereas the best recorded eye diagrams feature signal quality factors (Q-factors) above 7. While optical re-amplification was necessary to maintain the link budgets and therefore system measurements were performed with an erbium doped fiber amplifier (EDFA), preliminary characterization done with a semiconductor optical amplifier (SOA) indicates compatibility with the latter pending the integration of an additional optical filter to select a subset of carriers and prevent SOA saturation. A systematic analysis of the relative intensity noise (RIN) of isolated comb lines and of signal Q-factors indicates that the link is primarily limited by amplified spontaneous emission (ASE) from the EDFA rather than laser RIN. Measured RIN for single comb components is below -120 dBc/Hz in the range from 7 MHz to 4 GHz and drops to the shot noise level at higher frequencies.

  7. Semiconductor optical amplifier-based heterodyning detection for resolving optical terahertz beat-tone signals from passively mode-locked semiconductor lasers

    SciTech Connect

    Latkowski, Sylwester; Maldonado-Basilio, Ramon; Carney, Kevin; Parra-Cetina, Josue; Philippe, Severine; Landais, Pascal

    2010-08-23

    An all-optical heterodyne approach based on a room-temperature controlled semiconductor optical amplifier (SOA) for measuring the frequency and linewidth of the terahertz beat-tone signal from a passively mode-locked laser is proposed. Under the injection of two external cavity lasers, the SOA acts as a local oscillator at their detuning frequency and also as an optical frequency mixer whose inputs are the self-modulated spectrum of the device under test and the two laser beams. Frequency and linewidth of the intermediate frequency signal (and therefore, the beat-tone signal) are resolved by using a photodiode and an electrical spectrum analyzer.

  8. Towards the generation of random bits at terahertz rates based on a chaotic semiconductor laser

    NASA Astrophysics Data System (ADS)

    Kanter, Ido; Aviad, Yaara; Reidler, Igor; Cohen, Elad; Rosenbluh, Michael

    2010-06-01

    Random bit generators (RBGs) are important in many aspects of statistical physics and crucial in Monte-Carlo simulations, stochastic modeling and quantum cryptography. The quality of a RBG is measured by the unpredictability of the bit string it produces and the speed at which the truly random bits can be generated. Deterministic algorithms generate pseudo-random numbers at high data rates as they are only limited by electronic hardware speed, but their unpredictability is limited by the very nature of their deterministic origin. It is widely accepted that the core of any true RBG must be an intrinsically non-deterministic physical process, e.g. measuring thermal noise from a resistor. Owing to low signal levels, such systems are highly susceptible to bias, introduced by amplification, and to small nonrandom external perturbations resulting in a limited generation rate, typically less than 100M bit/s. We present a physical random bit generator, based on a chaotic semiconductor laser, having delayed optical feedback, which operates reliably at rates up to 300Gbit/s. The method uses a high derivative of the digitized chaotic laser intensity and generates the random sequence by retaining a number of the least significant bits of the high derivative value. The method is insensitive to laser operational parameters and eliminates the necessity for all external constraints such as incommensurate sampling rates and laser external cavity round trip time. The randomness of long bit strings is verified by standard statistical tests.

  9. Bidirectional chaos communication between two outer semiconductor lasers coupled mutually with a central semiconductor laser.

    PubMed

    Li, Ping; Wu, Jia-Gui; Wu, Zheng-Mao; Lin, Xiao-Dong; Deng, Dao; Liu, Yu-Ran; Xia, Guang-Qiong

    2011-11-21

    Based on a linear chain composed of a central semiconductor laser and two outer semiconductor lasers, chaos synchronization and bidirectional communication between two outer lasers have been investigated under the case that the central laser and the two outer lasers are coupled mutually, whereas there exists no coupling between the two outer lasers. The simulation results show that high-quality and stable isochronal synchronization between the two outer lasers can be achieved, while the cross-correlation coefficients between the two outer lasers and the central laser are very low under proper operation condition. Based on the high performance chaos synchronization between the two outer lasers, message bidirectional transmissions of bit rates up to 20 Gbit/s can be realized through adopting a novel decoding scheme which is different from that based on chaos pass filtering effect. Furthermore, the security of bidirectional communication is also analyzed.

  10. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers.

    PubMed

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-12-19

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing.

  11. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers

    PubMed Central

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-01-01

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing. PMID:27991574

  12. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers

    NASA Astrophysics Data System (ADS)

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-12-01

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing.

  13. Hybrid chaos-based communication system consisting of three chaotic semiconductor ring lasers.

    PubMed

    Li, Nianqiang; Pan, Wei; Xiang, Shuiying; Luo, Bin; Yan, Lianshan; Zou, Xihua

    2013-03-01

    We report on the realization of a hybrid chaos-based communication scheme using three chaotic semiconductor ring lasers (SRLs). In this scheme, two slave SRLs (S-SRLs) are identically driven by a master SRL (M-SRL) subject to delayed optical feedback. Under proper conditions, the S-SRLs are completely synchronized with each other due to the symmetric operation, and they are also synchronized with the M-SRL through the injection-locking effect. The results also show that a message encrypted through chaos shift keying at the M-SRL end can be successfully decrypted by the two S-SRLs, while the two uncoupled S-SRLs allow for dual-channel chaos communication when both counterpropagating modes of one S-SRL are encoded with a message.

  14. Synchronized 4 × 12 GHz hybrid harmonically mode-locked semiconductor laser based on AWG.

    PubMed

    Liu, S; Lu, D; Zhang, R; Zhao, L; Wang, W; Broeke, R; Ji, C

    2016-05-02

    We report a monolithically integrated synchronized four wavelength channel mode-locked semiconductor laser chip based on arrayed waveguide grating and fabricated in the InP material system. Device fabrication was completed in a multiproject wafer foundry run on the Joint European Platform for Photonic Integration of Components and Circuits. The integrated photonic chip demonstrated 5th harmonic electrical hybrid mode-locking operation with four 400 GHz spacing wavelength channels and synchronized to a 12.7 GHz RF clock, for nearly transform-limited optical pulse trains from a single output waveguide. A low timing jitter of 0.349 ps, and RF frequency locking range of ~50 MHz were also achieved.

  15. Quantitative analysis of uranium in aqueous solutions using a semiconductor laser-based spectroscopic method.

    PubMed

    Cho, Hye-Ryun; Jung, Euo Chang; Cha, Wansik; Song, Kyuseok

    2013-05-07

    A simple analytical method based on the simultaneous measurement of the luminescence of hexavalent uranium ions (U(VI)) and the Raman scattering of water, was investigated for determining the concentration of U(VI) in aqueous solutions. Both spectra were measured using a cw semiconductor laser beam at a center wavelength of 405 nm. The empirical calibration curve for the quantitative analysis of U(VI) was obtained by measuring the ratio of the luminescence intensity of U(VI) at 519 nm to the Raman scattering intensity of water at 469 nm. The limit of detection (LOD) in the parts per billion range and a dynamic range from the LOD up to several hundred parts per million were achieved. The concentration of uranium in groundwater determined by this method is in good agreement with the results determined by kinetic phosphorescence analysis and inductively coupled plasma mass spectrometry.

  16. Excitability in optically injected semiconductor lasers: Contrasting quantum- well- and quantum-dot-based devices

    NASA Astrophysics Data System (ADS)

    Kelleher, B.; Bonatto, C.; Huyet, G.; Hegarty, S. P.

    2011-02-01

    Excitability is a generic prediction for an optically injected semiconductor laser. However, the details of the phenomenon differ depending on the type of device in question. For quantum-well lasers very complicated multipulse trajectories can be found, while for quantum-dot lasers the situation is much simpler. Experimental observations show the marked differences in the pulse shapes while theoretical considerations reveal the underlying mechanism responsible for the contrast, identifying the increased stability of quantum-dot lasers to perturbations as the root.

  17. Excitability in optically injected semiconductor lasers: contrasting quantum-well- and quantum-dot-based devices.

    PubMed

    Kelleher, B; Bonatto, C; Huyet, G; Hegarty, S P

    2011-02-01

    Excitability is a generic prediction for an optically injected semiconductor laser. However, the details of the phenomenon differ depending on the type of device in question. For quantum-well lasers very complicated multipulse trajectories can be found, while for quantum-dot lasers the situation is much simpler. Experimental observations show the marked differences in the pulse shapes while theoretical considerations reveal the underlying mechanism responsible for the contrast, identifying the increased stability of quantum-dot lasers to perturbations as the root.

  18. A semiconductor-based, frequency-stabilized mode-locked laser using a phase modulator and an intracavity etalon.

    PubMed

    Davila-Rodriguez, Josue; Ozdur, Ibrahim; Williams, Charles; Delfyett, Peter J

    2010-12-15

    We report a frequency-stabilized semiconductor-based mode-locked laser that uses a phase modulator and an intracavity Fabry-Perot etalon for both active mode-locking and optical frequency stabilization. A twofold multiplication of the repetition frequency of the laser is inherently obtained in the process. The residual timing jitter of the mode-locked pulse train is 13 fs (1 Hz to 100 MHz), measured after regenerative frequency division of the photodetected pulse train.

  19. Optical arbitrary waveform generation based on multi-wavelength semiconductor fiber ring laser

    NASA Astrophysics Data System (ADS)

    Li, Peili; Ma, Xiaolu; Shi, Weihua; Xu, Enming

    2017-09-01

    A new scheme of generating optical arbitrary waveforms based on multi-wavelength semiconductor fiber ring laser (SFRL) is proposed. In this novel scheme, a wide and flat optical frequency comb (OFC) is provided directly by multi-wavelength SFRL, whose central frequency and comb spacing are tunable. OFC generation, de-multiplexing, amplitude and phase modulation, and multiplexing are implementing in an intensity and phase tunable comb filter, as induces the merits of high spectral coherence, satisfactory waveform control and low system loss. By using the mode couple theory and the transfer matrix method, the theoretical model of the scheme is established. The impacts of amplitude control, phase control, number of spectral line, and injection current of semiconductor optical amplifier (SOA) on the waveform similarity are studied using the theoretical model. The results show that, amplitude control and phase control error should be smaller than 1% and 0.64% respectively to achieve high similarity. The similarity of the waveform is improved with the increase of the number of spectral line. When the injection current of SOA is in a certain range, the optical arbitrary waveform reaches a high similarity.

  20. Mode Hopping in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Heumier, Timothy Alan

    Semiconductor lasers have found widespread use in fiberoptic communications, merchandising (bar-code scanners), entertainment (videodisc and compact disc players), and in scientific inquiry (spectroscopy, laser cooling). Some uses require a minimum degree of stability of wavelength which is not met by these lasers: Under some conditions, semiconductor lasers can discontinuously switch wavelengths in a back-and-forth manner. This is called mode hopping. We show that mode hopping is directly correlated to noise in the total intensity, and that this noise is easily detected by a photodiode. We also show that there are combinations of laser case temperature and injection current which lead to mode hopping. Conversely, there are other combinations for which the laser is stable. These results are shown to have implications for controlling mode hopping.

  1. Failure Mechanisms of High Temperature Semiconductor Lasers

    DTIC Science & Technology

    1993-12-01

    TEMPERATURE SEMICONDUCTOR LASERS L Background and Detiption of Anlyis Conducted This thesis describes and attempts to model the influence of elevated...for SC lasers. One such project is a laser-based solution for the growing complexity of the PAVE PACE Interboard Communications. This unit controls an...and grain boundaries. Thus dislocation lines will generally combine to form complex dislocation networks. dislocation line dislocation line H1Burgers

  2. Semiconductor Laser Tracking Frequency Distance Gauge

    NASA Technical Reports Server (NTRS)

    Phillips, James D.; Reasenberg, Robert D.

    2009-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require a spaceworthy laser distance gauge of substantially improved performance. The Tracking Frequency Gauge (TFG) uses a single beam, locking a laser to the measurement interferometer. We have demonstrated this technique with pm (10(exp -12) m) performance. We report on the version we are now developing based on space-qualifiable, fiber-coupled distributed-feedback semiconductor lasers.

  3. Semiconductor Laser Tracking Frequency Distance Gauge

    NASA Technical Reports Server (NTRS)

    Phillips, James D.; Reasenberg, Robert D.

    2009-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require a spaceworthy laser distance gauge of substantially improved performance. The Tracking Frequency Gauge (TFG) uses a single beam, locking a laser to the measurement interferometer. We have demonstrated this technique with pm (10(exp -12) m) performance. We report on the version we are now developing based on space-qualifiable, fiber-coupled distributed-feedback semiconductor lasers.

  4. Optical logic and signal processing using a semiconductor laser diode-based optical bistability device

    NASA Astrophysics Data System (ADS)

    Zhang, Yuancheng; Song, Qian; He, Shaowei

    1995-02-01

    Using an optical fibre-coupled semiconductor laser diode OBD with output feedback pumping operation in 5 modes (differential gain, bistability, zero-bias, inverted differential gain, and inverted bistability) has been realized respectively, and 5 elementary optical logic functions (AND, OR, NOT, NAND, and NOR) and some optical signal processing such as limiting, reshaping, and triggering have been implemented.

  5. Switchable dual-wavelength fiber laser based on semiconductor optical amplifier and polarization-maintaining fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Ren, Wenhua; Jian, Shuisheng

    2008-12-01

    Switchable dual-wavelength with orthogonal polarizations fiber laser based on semiconductor optical amplifier (SOA) and polarization-maintaining fiber Bragg grating (PMFBG) at room temperature is proposed. Owing to the polarization dependent loss of the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting the polarization controller (PC). The amplitude variation in nearly half an hour is less than 0.1 dB for both wavelengths, which is more stable than that of erbium doped fiber (EDF)-based laser with similar configuration.

  6. Guiding effect of quantum wells in semiconductor lasers

    SciTech Connect

    Aleshkin, V Ya; Dikareva, Natalia V; Dubinov, A A; Zvonkov, B N; Karzanova, Maria V; Kudryavtsev, K E; Nekorkin, S M; Yablonskii, A N

    2013-05-31

    The guiding effect of InGaAs quantum wells in GaAs- and InP-based semiconductor lasers has been studied theoretically and experimentally. The results demonstrate that such waveguides can be effectively used in laser structures with a large refractive index difference between the quantum well material and semiconductor matrix and a large number of quantum wells (e.g. in InP-based structures). (semiconductor lasers. physics and technology)

  7. Chaos synchronization based on a continuous chaos control method in semiconductor lasers with optical feedback.

    PubMed

    Murakami, A; Ohtsubo, J

    2001-06-01

    Chaos synchronization using a continuous chaos control method was studied in two identical chaotic laser systems consisting of semiconductor lasers and optical feedback from an external mirror. Numerical calculations for rate equations indicate that the stability of chaos synchronization depends significantly on the external mirror position. We performed a linear stability analysis for the rate equations. Our results show that the stability of the synchronization is much influenced by the mode interaction between the relaxation oscillation frequency of the semiconductor laser and the external cavity frequency. Due to this interaction, an intensive mode competition between the two frequencies destroys the synchronization, but stable synchronization can be achieved when the mode competition is very weak.

  8. Modeling of THz Lasers Based on Intersubband Transitions in Semiconductor Quantum Wells

    NASA Technical Reports Server (NTRS)

    Liu, Ansheng; Woo, Alex C. (Technical Monitor)

    1999-01-01

    In semiconductor quantum well structures, the intersubband energy separation can be adjusted to the terahertz (THz) frequency range by changing the well width and material combinations. The electronic and optical properties of these nanostructures can also be controlled by an applied dc electric field. These unique features lead to a large frequency tunability of the quantum well devices. In the on-going project of modeling of the THz lasers, we investigate the possibility of using optical pumping to generate THz radiation based on intersubband transitions in semiconductor quantum wells. We choose the optical pumping because in the electric current injection it is difficult to realize population inversion in the THz frequency range due to the small intersubband separation (4-40 meV). We considered both small conduction band offset (GaAs/AlGaAs) and large band offset (InGaAs/AlAsSb) quantum well structures. For GaAs/AlGaAs quantum wells, mid-infrared C02 lasers are used as pumping sources. For InGaAs/AlAsSb quantum wells, the resonant intersubband transitions can be excited by the near-infrared diode lasers. For three- and four-subband quantum wells, we solve the pumpfield-induced nonequilibrium distribution function for each subband of the quantum well system from a set of rate equations that include both intrasubband and intersubband relaxation processes. Taking into account the coherent interactions between pump and THz (signal) waves, we calculate the optical gain for the THz field. The gain arising from population inversion and stimulated Raman processes is calculated in a unified manner. A graph shows the calculated THz gain spectra for three-subband GaAs/AlGaAs quantum wells. We see that the coherent pump and signal wave interactions contribute significantly to the gain. The pump intensity dependence of the THz gain is also studied. The calculated results are shown. Because of the optical Stark effect and pump-induced population redistribution, the maximum

  9. Semiconductor processing with excimer lasers

    SciTech Connect

    Young, R.T.; Narayan, J.; Christie, W.H.; van der Leeden, G.A.; Rothe, D.E.; Cheng, L.J.

    1983-01-01

    The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at uv and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2 to 3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications.

  10. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

  11. Theory, Modeling, and Simulation of Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

  12. Semiconductor laser self-mixing micro-vibration measuring technology based on Hilbert transform

    NASA Astrophysics Data System (ADS)

    Tao, Yufeng; Wang, Ming; Xia, Wei

    2016-06-01

    A signal-processing synthesizing Wavelet transform and Hilbert transform is employed to measurement of uniform or non-uniform vibrations in self-mixing interferometer on semiconductor laser diode with quantum well. Background noise and fringe inclination are solved by decomposing effect, fringe counting is adopted to automatic determine decomposing level, a couple of exact quadrature signals are produced by Hilbert transform to extract vibration. The tempting potential of real-time measuring micro vibration with high accuracy and wide dynamic response bandwidth using proposed method is proven by both simulation and experiment. Advantages and error sources are presented as well. Main features of proposed semiconductor laser self-mixing interferometer are constant current supply, high resolution, simplest optical path and much higher tolerance to feedback level than existing self-mixing interferometers, which is competitive for non-contact vibration measurement.

  13. Diode-laser based scanning laser thermoelectric microscope for thermal diffusivity characterization of thin films on semiconductor substrates

    SciTech Connect

    Borca-Tasciuc, T.; Chen, G.

    1999-07-01

    This work presents new experimental results in the characterization of thermophysical properties for dielectric thin films on semiconductor substrates using the Scanning Laser Thermoelectric Microscope (SLTM) measurement technique. The new improved SLTM employs a modulated laser beam from a 1.55 {micro}m IR diode laser. The laser is used to create a micro-scale thermal wave in the film by focusing the light through the substrate. At this laser wavelength, the technique can be used to determine the thermal diffusivity for films deposited on semiconductor substrates with the band-gap larger than 0.8eV. The generated thermal wave is detected by a fast responding thermocouple formed between the film surface and the tip of a sharp probe. By scanning the laser beam around the thermocouple, the amplitude and phase distributions of the thermal wave are obtained. The film thermal diffusivity is obtained by fitting the detected phase profile of the thermal wave with a three-dimensional heat conduction model. Experimental results are presented for a film-on-substrate system composed of a two-layer thin film on the silicon substrate. The two-layer film is a 4.65{micro}m silicon dioxide film on which a 100nm thick gold film is deposited in order to provide an absorption layer for the laser light and also to facilitate the thermoelectric detection of the thermal wave.

  14. Mid-IR semiconductor lasers for chemical sensing

    NASA Technical Reports Server (NTRS)

    Hill, C. J.; Yang, R. Q.

    2003-01-01

    The development of mid-IR semiconductor diode lasers based on type-II interband cascade structures is presented. How these diode lasers can be developed to meet the requirements in chemical sensing applications is discussed.

  15. Mid-IR semiconductor lasers for chemical sensing

    NASA Technical Reports Server (NTRS)

    Hill, C. J.; Yang, R. Q.

    2003-01-01

    The development of mid-IR semiconductor diode lasers based on type-II interband cascade structures is presented. How these diode lasers can be developed to meet the requirements in chemical sensing applications is discussed.

  16. Tunable Infrared Semiconductor Lasers

    DTIC Science & Technology

    2013-12-20

    is a thulium fiber laser that has output of 20Watts at 1.908 µm with a collimated output beam diameter of about 5 mm. With a cylindrical lens, a...the device onto a copper heat sink and then to the cold finger of liquid nitrogen Dewar. In characterization, a thulium fiber laser at 1.908 nm

  17. Electron beam pumped semiconductor laser

    NASA Technical Reports Server (NTRS)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  18. 1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

    NASA Astrophysics Data System (ADS)

    Hansen, A. K.; Christensen, M.; Noordegraaf, D.; Heist, P.; Papastathopoulos, E.; Loyo-Maldonado, V.; Jensen, O. B.; Stock, M. L.; Skovgaard, P. M. W.

    2017-02-01

    Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction- limited, single frequency operation with output powers up to 8 W near 1120 nm. We present a 1.9 W single frequency laser system at 562 nm, based on single pass cascaded frequency doubling of such a tapered laser diode. The laser diode is a monolithic device consisting of two sections: a ridge waveguide with a distributed Bragg reflector, and a tapered amplifier. Using single-pass cascaded frequency doubling in two periodically poled lithium niobate crystals, 1.93 W of diffraction-limited light at 562 nm is generated from 5.8 W continuous-wave infrared light. When turned on from cold, the laser system reaches full power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination of high stability, compactness and watt-level power range means this technology is of great interest for a wide range of biological and biomedical applications.

  19. Frequency-modulated, tunable, semiconductor-optical-amplifier-based fiber ring laser for linewidth and line shape control.

    PubMed

    Girard, Simon Lambert; Chen, Hongxin; Schinn, Gregory W; Piché, Michel

    2008-08-15

    We report how the linewidth and line shape of a tunable semiconductor-optical-amplifier-based fiber ring laser can be actively adjusted by applying an intracavity frequency modulation to the laser. Frequency-modulated laser operation is achieved by driving the phase modulator frequency close to the cavity axial-mode spacing, leading to a constant-amplitude laser output having a periodically varying instantaneous frequency. The resulting linewidth varies proportionally with the inverse of the frequency detuning, and it is adjustable from submegahertz to over more than 5 GHz. By appropriate selection of the modulating waveform we have synthesized a near-Gaussian output line shape; other line shapes can be produced by modifying the modulating waveform. Experimental observations are in good agreement with a simple model.

  20. Compact ultrafast semiconductor disk laser: targeting GFP based nonlinear applications in living organisms

    PubMed Central

    Aviles-Espinosa, Rodrigo; Filippidis, George; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J.; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Santos, Susana I.C.O; Artigas, David; Loza-Alvarez, Pablo

    2011-01-01

    We present a portable ultrafast Semiconductor Disk Laser (SDL) (or vertical extended cavity surface emitting laser—VECSELs), to be used for nonlinear microscopy. The SDL is modelocked using a quantum-dot semiconductor saturable absorber mirror (SESAM), delivering an average output power of 287 mW, with 1.5 ps pulses at 500 MHz and a central wavelength of 965 nm. Specifically, despite the fact of having long pulses and high repetition rates, we demonstrate the potential of this laser for Two-Photon Excited Fluorescence (TPEF) imaging of in vivo Caenorhabditis elegans (C. elegans) expressing Green Fluorescent Protein (GFP) in a set of neuronal processes and cell bodies. Efficient TPEF imaging is achieved due to the fact that this wavelength matches the peak of the two-photon action cross section of this widely used fluorescent marker. The SDL extended versatility is shown by presenting Second Harmonic Generation images of pharynx, uterus, body wall muscles and its potential to be used to excite other different commercial dyes. Importantly this non-expensive, turn-key, compact laser system could be used as a platform to develop portable nonlinear bio-imaging devices. PMID:21483599

  1. Optical clock division based on dual-wavelength mode-locked semiconductor fiber ring laser.

    PubMed

    Zhang, Weiwei; Sun, Junqiang; Wang, Jian; Zhang, Xingliang; Huang, Dexiu

    2008-07-21

    We have reported the optical clock division utilizing an injected mode-locked fiber ring laser incorporating semiconductor optical amplifiers (SOAs) and a dispersion compensation fiber (DCF). The clock division is mainly caused by the modulation competition between two wavelength components while both of them satisfy the harmonic mode-locking condition at the newly generated frequency. Stable second, third, and fourth clock divisions are obtained by properly adjusting the polarization controllers inside the ring cavity when a 10-GHz clock signal without any sub-harmonic frequency component is injected into the cavity. The radio-frequency spectra show good qualities of the obtained clock division trains.

  2. Study of multiwavelength DFB semiconductor laser array with asymmetric structures based on sampling technique.

    PubMed

    Shi, Yuechun; Cao, Baoli; Li, Lianyan; Tang, Song; Zheng, Junshou; Zhang, Peng; Chen, Ting; Liu, Shengchun

    2014-10-10

    Multiwavelength distributed feedback (DFB) semiconductor laser arrays (MLA) with asymmetric structures are studied in this paper. Thanks to the sampling technique, the asymmetric structures, including asymmetric phase shift and asymmetric coupling coefficient, can be achieved by common holographic exposure. Therefore, the cost of fabrication is remarkably reduced. In addition, due to the large scale of the sampling pattern, the wavelength precision of these kinds of MLA can be simultaneously improved. As an example, we designed and fabricated an asymmetrically phase-shifted MLA with 10 wavelengths for the first time. Compared with the common phase-shifted DFB laser, slope efficiency is significantly improved and single longitudinal mode is still guaranteed. Besides, relatively high wavelength precision is also obtained. The proposed MLA configurations may significantly benefit multiwavelength emitters for future photonic integration.

  3. Selection of modes in transverse-mode waveguides for semiconductor lasers based on asymmetric heterostructures

    SciTech Connect

    Slipchenko, S. O. Bondarev, A. D.; Vinokurov, D. A.; Nikolaev, D. N.; Fetisova, N. V.; Sokolova, Z. N.; Pikhtin, N. A.; Tarasov, I. S.

    2009-01-15

    Asymmetric Al{sub 0.3}Ga{sub 0.7}As/GaAs/InGaAs heterostructures with a broadened waveguide produced by the method of MOCVD epitaxy are studied. It is established that the precision shift of the active region to one of the cladding layers ensures the generation of the chosen mode of high order in the transverse broadened waveguide. It is experimentally established that this shift brings about an increase in internal optical losses and a decrease in the internal quantum efficiency of stimulated emission. It is shown experimentally that the shift of the active region to the n-type cladding layer governs the sublinear form of the power-current characteristic for semiconductor lasers; in the case of a shift of the active region towards the p-type cladding layer, the laser diodes demonstrated a linear dependence of optical power on the pump current in the entire range of pump currents.

  4. Semiconductor laser device

    SciTech Connect

    Namizaki, H.; Susaki, W.; Takamiya, S.; Tanaka, T.

    1981-07-07

    A first N-AlGaAs and a second N-GaAs layer are successively grown on an I-GaAs substrate. A third N-AlGaAs, a fourth P-AlGaAs and a fifth N-GaAs layer superpose one another on the second layer except for one lateral portion. Those portions of the five layers remote from the exposed second layer portion are changed into a P+ type and surrounded by a P zone. A positive and a negative electrode are located on the fifth layer and the exposed second layer portion, respectively. The negative electrode is nearest to a laser region located in the second layer and can be secured to a heat sink.

  5. TUNABLE RING LASER BASED ON A SEMICONDUCTOR OPTICAL AMPLIFIER AT 1300 NM USING A SIMPLE WAVELENGTH SELECTION FILTER

    PubMed Central

    Jeon, Mansik; Kim, Jeehyun; Song, Jae-Won; Lee, Ho; Choi, Sanghoon; Nelson, J. Stuart

    2009-01-01

    A simple, compact, and low cost tunable ring laser with a commercial semiconductor optical amplifier (SOA) was demonstrated. The tunable ring laser is based on an external wavelength filter cavity that is analogous with the Littman configuration with a diffraction grating, a mirror, and a simple slit. The unique structural advantage of this new system is that the slit is displaced to select a desired wavelength instead of tilting the mirror as in the Littman configuration. This allows easy control over the selected wavelength by the translating action of the slit. The full width half maximum (FWHM) wavelength turning range is 45 nm, and the wavelength resolution is about 2 pm. The demonstrated tunable ring laser has 2 mW output power. The side mode suppression ratios is 70–73 dB. PMID:20539831

  6. EDITORIAL: Semiconductor lasers: the first fifty years Semiconductor lasers: the first fifty years

    NASA Astrophysics Data System (ADS)

    Calvez, S.; Adams, M. J.

    2012-09-01

    Anniversaries call for celebrations. Since it is now fifty years since the first semiconductor lasers were reported, it is highly appropriate to celebrate this anniversary with a Special Issue dedicated to the topic. The semiconductor laser now has a major effect on our daily lives since it has been a key enabler in the development of optical fibre communications (and hence the internet and e-mail), optical storage (CDs, DVDs, etc) and barcode scanners. In the early 1960s it was impossible for most people (with the exception of very few visionaries) to foresee any of these future developments, and the first applications identified were for military purposes (range-finders, target markers, etc). Of course, many of the subsequent laser applications were made possible by developments in semiconductor materials, in the associated growth and fabrication technology, and in the increased understanding of the underlying fundamental physics. These developments continue today, so that the subject of semiconductor lasers, although mature, is in good health and continues to grow. Hence, we can be confident that the pervasive influence of semiconductor lasers will continue to develop as optoelectronics technology makes further advances into other sectors such as healthcare, security and a whole host of applications based on the global imperatives to reduce energy consumption, minimise environmental impact and conserve resources. The papers in this Special Issue are intended to tell some of the story of the last fifty years of laser development as well as to provide evidence of the current state of semiconductor laser research. Hence, there are a number of papers where the early developments are recalled by authors who played prominent parts in the story, followed by a selection of papers from authors who are active in today's exciting research. The twenty-fifth anniversary of the semiconductor laser was celebrated by the publication of a number of papers dealing with the early

  7. Optical complexity in external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Rondoni, Lamberto; Ariffin, M. R. K.; Varatharajoo, Renuganth; Mukherjee, Sayan; Palit, Sanjay K.; Banerjee, Santo

    2017-03-01

    In this article, the window based complexity and output modulation of a time delayed chaotic semiconductor laser (SL) model has been investigated. The window based optical complexity (OC), is measured by introducing the recurrence sample entropy (SampEn). The analysis has been done without and in the presence of external noise. The significant changes in the dynamics can be observed under induced noise with weak strength. It has also been found that there is a strong positive correlation between the output power and the complexity of the system with various sets of parameters. The laser intensity, as well as the OC can be increased with the incremental noise strength and the associated system parameters. Thus, optical complexity quantifies the system dynamics and its instabilities, since is strongly correlated with the laser outputs. This analysis can be applied to measure the laser instabilities and modulation of output power.

  8. A temperature sensor based on switchable dual-wavelength fiber Bragg grating laser with a semiconductor saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Li, Qi; Huang, Kai-qiang; Chen, Hai-yan

    2015-11-01

    A temperature sensor based on a switchable dual-wavelength fiber Bragg grating (FBG) laser with a semiconductor saturable absorber mirror (SESAM) is presented and demonstrated experimentally. The repetition rate of Q-switched pulses is ~17 kHz. The results demonstrate that the measured temperature has good linearity to the wavelength spacing of the two lasing wavelengths and has a temperature sensitivity of 21 pm/ºC covering a range of -10—22 °C. The experimental results prove the feasibility of the proposed temperature sensor.

  9. Optical isolator for semiconductor lasers.

    PubMed

    Kuwahara, H

    1980-01-15

    An optical isolator for semiconductor lasers, consisting of a polarizer and a quarterwave plate, was investigated experimentally. It was assembled in a compact laser-to-fiber coupling module. Experiment showed forward loss of 1.15 dB, backward loss of 24.8 dB, and rotative tolerance of 2.4 deg for 1 dB down. The length of the module is 43.2 mm. The coupling efficiency to a graded-index multimode fiber is 37.5%. The extinction ratio is improved by 6.75 dB. The suppression effect on the influence of reflected light was investigated, using the assembled module.

  10. Tunable and switchable multi-wavelength fiber laser based on semiconductor optical amplifier and twin-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Han, Jihee; Chung, Youngjoo

    2012-02-01

    Multi-wavelength fiber lasers have attracted a lot of interest, recently, because of their potential applications in wavelength-division-multiplexing (WDM) systems, optical fiber sensing, and fiber-optics instruments, due to their numerous advantages such as multiple wavelength operation, low cost, and compatibility with the fiber optic systems. Semiconductor optical amplifier (SOA)-based multi-wavelength fiber lasers exhibit stable operation because of the SOA has the property of primarily inhomogeneous broadening and thus can support simultaneous oscillation of multiple lasing wavelengths. In this letter, we propose and experimentally demonstrate a switchable multi-wavelength fiber laser employing a semiconductor optical amplifier and twin-core photonic crystal fiber (TC-PCF) based in-line interferometer comb filter. The fabricated two cores are not symmetric due to the associated fiber fabrication process such as nonuniform heat gradient in furnace and asymmetric microstructure expansion during the gas pressurization which results in different silica strut thickness and core size. The induced asymmetry between two cores considerably alters the linear power transfer, by seriously reducing it. These nominal twin cores form effective two optical paths and associated effective refractive index difference. The in-fiber comb filter is effectively constructed by splicing a section of TC-PCF between two single mode fibers (SMFs). The proposed laser can be designed to operate in stable multi-wavelength lasing states by adjusting the states of the polarization controller (PC). The lasing modes are switched by varying the state of PC and the change is reversible. In addition, we demonstrate a tunable multi-wavelength fiber laser operation by applying temperature changes to TC-PCF in the multi-channel filter.

  11. Characterization of wavelength-swept active mode locking fiber laser based on reflective semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Lee, Hwi Don; Lee, Ju Han; Yung Jeong, Myung; Kim, Chang-Seok

    2011-07-01

    The static and dynamic characteristics of a wavelength-swept active mode locking (AML) fiber laser are presented in both the time-region and wavelength-region. This paper shows experimentally that the linewidth of a laser spectrum and the bandwidth of the sweeping wavelength are dependent directly on the length and dispersion of the fiber cavity as well as the modulation frequency and sweeping rate under the mode-locking condition. To achieve a narrower linewidth, a longer length and higher dispersion of the fiber cavity as well as a higher order mode locking condition are required simultaneously. For a broader bandwidth, a lower order of the mode locking condition is required using a lower modulation frequency. The dynamic sweeping performance is also analyzed experimentally to determine its applicability to optical coherence tomography imaging. It is shown that the maximum sweeping rate can be improved by the increased free spectral range from the shorter length of the fiber cavity. A reflective semiconductor optical amplifier (RSOA) was used to enhance the modulation and dispersion efficiency. Overall a triangular electrical signal can be used instead of the sinusoidal signal to sweep the lasing wavelength at a high sweeping rate due to the lack of mechanical restrictions in the wavelength sweeping mechanism.

  12. REVIEW High-power semiconductor separate-confinement double heterostructure lasers

    NASA Astrophysics Data System (ADS)

    Tarasov, I. S.

    2010-10-01

    The review is devoted to high-power semiconductor lasers. Historical reference is presented, physical and technological foundations are considered, and the concept of high-power semiconductor lasers is formulated. Fundamental and technological reasons limiting the optical power of a semiconductor laser are determined. The results of investigations of cw and pulsed high-power semiconductor lasers are presented. Main attention is paid to inspection of the results of experimental studies of single high-power semiconductor lasers. The review is mainly based on the data obtained in the laboratory of semiconductor luminescence and injection emitters at the A.F. Ioffe Physicotechnical Institute.

  13. The optically pumped semiconductor membrane external-cavity surface-emitting laser (MECSEL): a concept based on a diamond-sandwiched active region

    NASA Astrophysics Data System (ADS)

    Kahle, Hermann; Mateo, Cherry May N.; Brauch, Uwe; Bek, Roman; Jetter, Michael; Graf, Thomas; Michler, Peter

    2017-02-01

    Semiconductor disk lasers with all their advantages1 became an important stand-alone class of solid-state lasers during the last years. However, these systems suffer from heat incorporation into the active region caused by the excess energy of the pump photons. To overcome this limitation we realized the semiconductor membrane external-cavity surface-emitting laser as a diamond heat spreader sandwiched active region design. A detailed process description towards the MECSEL2 approach is given as well as fundamental performance values. Furthermore, parasitic lateral lasing effects are discovered and investigated. Nevertheless, the MECSEL approach indicates enormous potential to revolutionize the semiconductor based disk lasers regarding available output powers at room temperature and material combinations.

  14. Semiconductor disk laser-pumped subpicosecond holmium fibre laser

    SciTech Connect

    Chamorovskiy, A Yu; Marakulin, A V; Leinonen, T; Kurkov, Andrei S; Okhotnikov, Oleg G

    2012-01-31

    The first passively mode-locked holmium fibre laser has been demonstrated, with a semiconductor saturable absorber mirror (SESAM) as a mode locker. Semiconductor disk lasers have been used for the first time to pump holmium fibre lasers. We obtained 830-fs pulses at a repetition rate of 34 MHz with an average output power of 6.6 mW.

  15. Tunable high-power narrow-linewidth semiconductor laser based on an external-cavity tapered amplifier.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Holm, Jesper; Pedersen, Christian; Andersen, Peter Eskil; Erbert, Götz; Sumpf, Bernd; Petersen, Paul Michael

    2005-12-26

    A high-power narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The external cavity laser system uses a new tapered amplifier with a super-large optical-cavity (SLOC) design that leads to improved performance of the external cavity diode lasers. The laser system is tunable over a 29 nm range centered at 802 nm. As high as 1.95 W output power is obtained at 803.84 nm, and an output power above 1.5 W is achieved from 793 to 812 nm at operating current of 3.0 A. The emission linewidth is below 0.004 nm and the beam quality factor M2 is below 1.3 over the 29 nm tunable range. As an example of application, the laser system is used as a pump source for the generation of 405 nm blue light by single-pass frequency doubling in a periodically poled KTiOPO4. An output power of 24 mW at 405 nm, corresponding to a conversion efficiency of 0.83%/W is attained.

  16. Dual-wavelength distributed Bragg reflector semiconductor laser based on a composite resonant cavity

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Zhao, Ling-Juan; Qiu, Ji-Fang; Liu, Yang; Wang, Wei; Lou, Cai-Yun

    2012-09-01

    We report a monolithic integrated dual-wavelength laser diode based on a distributed Bragg reflector (DBR) composite resonant cavity. The device consists of three sections, a DBR grating section, a passive phase section, and an active gain section. The gain section facet is cleaved to work as a laser cavity mirror. The other laser mirror is the DBR grating, which also functions as a wavelength filter and can control the number of wavelengths involved in the laser action. The reflection bandwidth of the DBR grating is fabricated to have an appropriate value to make the device work at the dual-wavelength lasing state. We adopt the quantum well intermixing (QWI) technique to provide low-absorption loss grating and passive phase section in the fabrication process. By tuning the injection currents on the DBR and the gain sections, the device can generate 0.596 nm-spaced dual-wavelength lasing at room temperature.

  17. REVIEW ARTICLE: Harmonically mode-locked semiconductor-based lasers as high repetition rate ultralow noise pulse train and optical frequency comb sources

    NASA Astrophysics Data System (ADS)

    Quinlan, F.; Ozharar, S.; Gee, S.; Delfyett, P. J.

    2009-10-01

    Recent experimental work on semiconductor-based harmonically mode-locked lasers geared toward low noise applications is reviewed. Active, harmonic mode-locking of semiconductor-based lasers has proven to be an excellent way to generate 10 GHz repetition rate pulse trains with pulse-to-pulse timing jitter of only a few femtoseconds without requiring active feedback stabilization. This level of timing jitter is achieved in long fiberized ring cavities and relies upon such factors as low noise rf sources as mode-lockers, high optical power, intracavity dispersion management and intracavity phase modulation. When a high finesse etalon is placed within the optical cavity, semiconductor-based harmonically mode-locked lasers can be used as optical frequency comb sources with 10 GHz mode spacing. When active mode-locking is replaced with regenerative mode-locking, a completely self-contained comb source is created, referenced to the intracavity etalon.

  18. Towards Laser Cooling of Semiconductors

    NASA Astrophysics Data System (ADS)

    Hassani nia, Iman

    This dissertation reports on novel theoretical concepts as well as experimental efforts toward laser cooling of semiconductors. The use of quantum well system brings the opportunity to engineer bandstructure, effective masses and the spatial distribution of electrons and holes. This permits the incorporation of novel quantum mechanical phenomena to manipulate the temperature change of the material upon light-matter interaction. Inspired by the fact that Coulomb interaction can lead to blueshift of radiation after photo-absorption, the theory of Coulomb assisted laser cooling is proposed and investigated for the first time. In order to design suitable multiple quantum well (MQW) structures with Coulomb interaction a Poisson-Schrodinger solver was devised using MATLAB software. The software is capable of simulating all III-V material compositions and it results have been confirmed experimentally. In the next step, different MQW designs were proposed and optimized to exploit Coulomb interaction for assisting of optical refrigeration. One of the suitable designs with standard InGaAsP/InAlAs/InP layers was used to grow the MQW structures using metal organic vapor deposition (MOCVD). Novel techniques of fabrication were implemented to make suspended structures for detecting ultralow thermal powers. By fabricating accurate thermometers, the temperature changes of the device upon laser absorption were measured. The accurate measurement of the temperature encouraged us to characterize the electrical response of the device as another important tool to promote our understanding of the 4 underlying physical phenomena. This is in addition to the accurate spectral and time-resolved photoluminescence measurements that provided us with a wealth of information about the effects of stress, Auger recombination and excitonic radiance in such structures. As the future works, important measurements for finding the quantum efficiency of the devices via electrical characterization and

  19. Tbits/s physical random bit generation based on mutually coupled semiconductor laser chaotic entropy source.

    PubMed

    Tang, Xi; Wu, Zheng-Mao; Wu, Jia-Gui; Deng, Tao; Chen, Jian-Jun; Fan, Li; Zhong, Zhu-Qiang; Xia, Guang-Qiong

    2015-12-28

    Using two mutually coupled semiconductor lasers (MC-SLs) outputs as chaotic entropy sources, a scheme for generating Tbits/s ultra-fast physical random bit (PRB) is demonstrated and analyzed experimentally. Firstly, two entropy sources originating from two chaotic outputs of MC-SLs are obtained in parallel. Secondly, by adopting multiple optimized post-processing methods, two PRB streams with the generation rate of 0.56 Tbits/s are extracted from the two entropy sources and their randomness are verified by using NIST Special Publication 800-22 statistical tests. Through merging the two sets of 0.56 Tbits/s PRB streams by an interleaving operation, a third set of 1.12 Tbits/s PRB stream, which meets all the quality criteria of NIST statistical tests, can be further acquired. Finally, after additionally taking into account the restriction of the min-entropy, the generation rate of two sets of PRB stream from the two entropy sources can still attain 0.48 Tbits/s, and then a third set of merging PRB stream is 0.96 Tbits/s. Moreover, for the sequence length of the order of 10 Gbits, the statistical bias and serial correlation coefficient of three sets of PRB streams are also analyzed.

  20. Frequency modulation of semiconductor disk laser pulses

    SciTech Connect

    Zolotovskii, I O; Korobko, D A; Okhotnikov, O G

    2015-07-31

    A numerical model is constructed for a semiconductor disk laser mode-locked by a semiconductor saturable absorber mirror (SESAM), and the effect that the phase modulation caused by gain and absorption saturation in the semiconductor has on pulse generation is examined. The results demonstrate that, in a laser cavity with sufficient second-order dispersion, alternating-sign frequency modulation of pulses can be compensated for. We also examine a model for tuning the dispersion in the cavity of a disk laser using a Gires–Tournois interferometer with limited thirdorder dispersion. (control of radiation parameters)

  1. Semiconductor Lasers and Their Application in Optical Fiber Communication.

    ERIC Educational Resources Information Center

    Agrawal, Govind P.

    1985-01-01

    Working principles and operating characteristics of the extremely compact and highly efficient semiconductor lasers are explained. Topics include: the p-n junction; Fabry-Perot cavity; heterostructure semiconductor lasers; materials; emission characteristics; and single-frequency semiconductor lasers. Applications for semiconductor lasers include…

  2. Semiconductor Lasers and Their Application in Optical Fiber Communication.

    ERIC Educational Resources Information Center

    Agrawal, Govind P.

    1985-01-01

    Working principles and operating characteristics of the extremely compact and highly efficient semiconductor lasers are explained. Topics include: the p-n junction; Fabry-Perot cavity; heterostructure semiconductor lasers; materials; emission characteristics; and single-frequency semiconductor lasers. Applications for semiconductor lasers include…

  3. Laser method for simulating the transient radiation effects of semiconductor

    NASA Astrophysics Data System (ADS)

    Li, Mo; Sun, Peng; Tang, Ge; Wang, Xiaofeng; Wang, Jianwei; Zhang, Jian

    2017-05-01

    In this paper, we demonstrate the laser simulation adequacy both by theoretical analysis and experiments. We first explain the basic theory and physical mechanisms of laser simulation of transient radiation effect of semiconductor. Based on a simplified semiconductor structure, we describe the reflection, optical absorption and transmission of laser beam. Considering two cases of single-photon absorption when laser intensity is relatively low and two-photon absorption with higher laser intensity, we derive the laser simulation equivalent dose rate model. Then with 2 types of BJT transistors, laser simulation experiments and gamma ray radiation experiments are conducted. We found good linear relationship between laser simulation and gammy ray which depict the reliability of laser simulation.

  4. Superradiance dynamics in semiconductor laser diode structures.

    PubMed

    Boiko, D L; Vasil'ev, P P

    2012-04-23

    We analyze theoretically the superradiant emission (SR) in semiconductor edge-emitting laser heterostructures using InGaN/GaN heterostructure quantum well (QW) as a model system. The generation of superradiant pulses as short as 500 fs at peak powers of over 200 W has been predicted for InGaN/GaN heterostructure QWs with the peak emission in the blue/violet wavelength range. Numerical simulations based on semiclassical traveling wave Maxwell-Bloch equations predict building up of macroscopic coherences in the ensemble of electrons and holes during SR pulse formation. We show that SR is covered by the Ginzburg-Landau equation for a phase transition to macroscopically coherent state of matter. The presented theory is applicable to other semiconductor materials.

  5. Semiconductor laser applications in rheumatology

    NASA Astrophysics Data System (ADS)

    Pascu, Mihail-Lucian; Suteanu, S.

    1996-01-01

    Two types of laser diode (LD) based equipment for rheumatology are introduced. The first is a portable device which contains single LD emitting at 890 nm laser pulses (time full width 100 nsec) of reprate tunable within (0.5 - 1.5) kHz; the laser beam average power is 0.7 mW at 1 kHz reprate. The second is computer controlled, contains one HeNe laser and 5 LD allowing 6 modes of patient irradiation (placebo effect evaluation included). HeNe laser works in cw at 632.8 nm; the LD works each as described for the portable equipment. HeNe and LD beams are superposed so that HeNe laser spot in the irradiation plane has a 60 mm diameter and the LD spots covers a 50 mm diameter disc centered on the HeNe laser spot. Clinical applications using the second type of equipment are reported; 1287 patients were treated between October 1991 and October 1994. Female/male ratio was 4:1 and their age distribution was between 18 and 85 years. The average number of exposures was 10 and the mean exposure time was 7 minutes. Studies were made on the treatment of rheumatoid arthritis, seronegative arthritis, degenerative joint diseases, abarticular rheumatism, osteoporosis pain and pains and edema after fractures.

  6. Dissipative Phase Solitons in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Gustave, F.; Columbo, L.; Tissoni, G.; Brambilla, M.; Prati, F.; Kelleher, B.; Tykalewicz, B.; Barland, S.

    2015-07-01

    We experimentally demonstrate the existence of nondispersive solitary waves associated with a 2 π phase rotation in a strongly multimode ring semiconductor laser with coherent forcing. Similarly to Bloch domain walls, such structures host a chiral charge. The numerical simulations based on a set of effective Maxwell-Bloch equations support the experimental evidence that only one sign of chiral charge is stable, which strongly affects the motion of the phase solitons. Furthermore, the reduction of the model to a modified Ginzburg-Landau equation with forcing demonstrates the generality of these phenomena and exposes the impact of the lack of parity symmetry in propagative optical systems.

  7. Third order mode optically pumped semiconductor laser

    NASA Astrophysics Data System (ADS)

    De Rossi, A.; Semaltianos, N.; Chirlias, E.; Vinter, B.; Ortiz, V.; Berger, V.

    2002-06-01

    Lasing action on a third order waveguide mode is demonstrated at room temperature under optical pumping, in a specifically designed quantum well laser structure. The AlGaAs heterostructure involves barriers which ensure that the third order waveguide mode has a higher overlap with the single quantum well emitter than the fundamental mode. Third order mode operation of a laser structure opens the way to modal phase matched parametric down conversion inside the semiconductor laser itself. It is a first step towards the realization of semiconductor twin photon laser sources, needed for quantum information experiments.

  8. Integrated optics approach for advanced semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Suematsu, Yasuharu; Arai, Shigehisa

    1987-11-01

    Recent advances in the field of semiconductor integrated optics are reviewed from the point of view of monolithic integration of semiconductor lasers and other optical components and/or devices. Emphasis is placed on dynamic-single-mode (DSM) lasers, such as DFB and DBR lasers, intended for highly stable single-wavelength light sources for such monolithic integration. The realization of high-performance DSM lasers and the fabrication techniques of monolithically integrated optical devices and circuits are briefly reviewed. A variety of potential applications is discussed.

  9. A novel approach for generating flat optical frequency comb based on externally injected gain-switching distributed feedback semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhu, Huatao; Wang, Rong; Pu, Tao; Xiang, Peng; Zheng, Jilin; Fang, Tao

    2017-02-01

    In this paper, a novel approach for generating flat optical frequency comb (OFC) based on externally injected gain-switched distributed feedback (DFB) semiconductor laser is proposed and experimentally demonstrated. In the proposed system, the flatness, the number of OFC spectral lines, and the spectral line to background noise ratio can be tuned to their optimized values by adjusting the current of the modulation signal, the injection ratio and the detuning frequency. Since the frequency of the modulation signal decides the frequency spacing of the output spectral lines, OFC spectral lines of different spacing can be achieved. In the experiment, 10 spectral lines with 1.5 dB power variation are demonstrated to verify the proposed approach. In addition, the expansion of the spectral line is investigated.

  10. High power semiconductor lasers for deep space communications

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1981-01-01

    The parameters of semiconductor lasers pertaining to their application as optical emitters are discussed. Several methods to overcome their basic disadvantage, which is the low level of powers they emit, are reviewed. Most of these methods are based on a coherent power combining of several lasers.

  11. Ultrashort pulse generation in semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Auyeung, J.; Johnston, A. R.

    1981-01-01

    Techniques to generate picosecond optical pulses from semiconductor lasers are reviewed. Experimental methods and results of theoretical analysis of active modelocking are presented. It is shown that modelocking will achieve the shortest pulses; but the use of a cumbersome external cavity will probably limit its practical use. Short pulses produced by direct modulation such as gain switching are considerably broader than those obtained by passive modelocking. However, no external cavity is needed; and the simplicity of this method makes it important to be explored further. Recent experimental results are discussed where picosecond pulses from a buried heterostructure laser diode with ultrashort current pulses obtained from a comb generator are generated. Also, 28 ps pulses were obtained at 2.5 GHz repetition frequency, using the gain switching method. An analytical analysis based on the rate equations shows qualitative agreement with our experimental results.

  12. A 1.33 µm picosecond pulse generator based on semiconductor disk mode-locked laser and bismuth fiber amplifier.

    PubMed

    Heikkinen, Juuso; Gumenyuk, Regina; Rantamäki, Antti; Leinonen, Tomi; Melkumov, Mikhail; Dianov, Evgeny M; Okhotnikov, Oleg G

    2014-05-19

    We demonstrate that a combination of ultrafast wafer bonded semiconductor disk laser and a bismuth-doped fiber amplifier provides an attractive design for high power 1.33 µm tandem hybrid systems. Over 0.5 W of average output power was achieved at a repetition rate of 827 MHz that corresponds to a pulse energy of 0.62 nJ.

  13. Investigating the effects of capping layer on optical gain of nitride based semiconductor nanostructure lasers

    NASA Astrophysics Data System (ADS)

    Annabi Milani, E.; Mohadesi, V.; Asgari, A.

    2017-04-01

    In this study, the effects of GaN capping layer on the behaviour of AlGaN/GaN nanostructure based laser is considered. We have employed the self-consistent solution of Poisson and Schrodinger equations for calculation of the energy levels, wave functions and conduction and valance bands profile. The impact of different thicknesses of the capping layer has been studied for sheet carrier density, then on optical gain. The results indicate that, by increasing the thickness of the cap layer, the optical gain decreases.

  14. Semiconductor laser with multiple lasing wavelengths

    DOEpatents

    Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.

    2003-07-29

    A new class of multi-terminal vertical-cavity semiconductor laser components has been developed. These multi-terminal laser components can be switched, either electrically or optically, between distinct lasing wavelengths, or can be made to lase simultaneously at multiple wavelengths.

  15. Semiconductor laser gyro with optical frequency dithering

    SciTech Connect

    Prokof'eva, L P; Sakharov, V K; Shcherbakov, V V

    2014-04-28

    The semiconductor laser gyro is described, in which the optical frequency dithering implemented by intracavity phase modulation suppresses the frequency lock-in and provides the interference of multimode radiation. The sensitivity of the device amounted to 10–20 deg h{sup -1}. (laser gyroscopes)

  16. Infrared semiconductor laser based trace gas sensor technologies: recent advances and applications

    NASA Astrophysics Data System (ADS)

    Tittel, Frank K.; Curl, Robert F.; Dong, Lei; Lewicki, Rafal

    2011-05-01

    Recent advances in the development of trace gas sensors based on the use of quantum cascade lasers (QCLs) for the sensitive, selective detection, quantification and monitoring of small molecular gas species with resolved spectroscopic features will be described. High detection sensitivity at ppbv and sub-ppbv concentration levels require detection sensitivity, enhancement schemes such as multipass absorption cells, cavity enhanced absorption techniques, or quartz enhanced photo-acoustic absorption spectroscopy (QEPAS). These three spectroscopic methods can achieve minimum detectable absorption losses in the range from 10-8 to 10-11 cm-1/√Hz. Two recent examples of real world applications of field deployable PAS and QEPAS based gas sensors will be reported, namely the monitoring of ammonia concentrations in exhaled human breath and major urban environments.

  17. Mid- infrared semiconductor laser based trace gas sensor technologies for environmental monitoring and industrial process control

    NASA Astrophysics Data System (ADS)

    Lewicki, Rafał; Jahjah, Mohammad; Ma, Yufei; Tittel, Frank K.; Stefanski, Przemyslaw; Tarka, Jan

    2013-01-01

    Recent advances in the development of compact sensors based on mid-infrared continuous wave (CW), thermoelectrically cooled (TEC) and room temperature operated quantum cascade lasers (QCLs) for the detection, quantification and monitoring of trace gas species and their applications in environmental and industrial process analysis will be reported. These sensors employ a 2f wavelength modulation (WM) technique based on quartz enhanced photoacoustic spectroscopy (QEPAS) that achieves detection sensitivity at the ppb and sub ppb concentration levels. The merits of QEPAS include an ultra-compact, rugged sensing module, with wide dynamic range and immunity to environmental acoustic noise. QCLs are convenient QEPAS excitation sources that permit the targeting of strong fundamental rotational-vibrational transitions which are one to two orders of magnitude more intense in the mid-infrared than overtone transitions in the near infrared spectral region.

  18. Wavelength-tunable 10 GHz actively harmonic mode-locked fiber laser based on semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Mao, Yan; Tong, Xinglin; Wang, Zhiqiang; Zhan, Li; Hu, Pan; Chen, Liang

    2015-12-01

    We demonstrate a widely wavelength-tunable actively mode-locked fiber laser based on semiconductor optical amplifier. Beneficiating from the actively mode-locking operation and the wavelength-tunable characteristics of a Fabry-Perot filter, different harmonic mode-locking orders, from the fundamental mode-locking order (18.9 MHz) to the 520th order (9.832 GHz), can be easily achieved. The spectral bandwidth corresponding to the fundamental repetition rate is 0.12 nm with the pulse duration of 9.8 ns, leading to the TBP value of 146, which is about 460 times the transform-limited value for soliton pulse. The highest repetition rate of the mode-locked pulses we obtained is 9.832 GHz, with a signal-to-noise ratio up to 50 dB. The theoretical transform-limited pulse duration is 21 ps. Meanwhile, the central wavelength can be continuously tuned over 43.4 nm range (1522.8-1566.2 nm). The higher repetition rate and the widely tuning wavelength range make the fiber laser to own great potential and promising prospects in areas such as optical communication and photonic analog-to-digital conversion (ADC).

  19. Synchronization of semiconductor laser arrays with 2D Bragg structures

    NASA Astrophysics Data System (ADS)

    Baryshev, V. R.; Ginzburg, N. S.

    2016-08-01

    A model of a planar semiconductor multi-channel laser is developed. In this model two-dimensional (2D) Bragg mirror structures are used for synchronizing radiation of multiple laser channels. Coupling of longitudinal and transverse waves can be mentioned as the distinguishing feature of these structures. Synchronization of 20 laser channels is demonstrated with a semi-classical approach based on Maxwell-Bloch equations.

  20. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    SciTech Connect

    Deri, R J

    2011-01-03

    Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a {approx} 200 {micro}s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and

  1. Advances in high power semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  2. Laser Assisted Semiconductor Device Processing

    DTIC Science & Technology

    1980-11-30

    In strongly absorbing semiconductors, the dominant absorption mechanism at frequencies higher than the bandgap frequency is interband transitions. The...current). The solution for miconductors. In strongly absorbing semiconductors, the n(x,t ) is a closed-form expression consisting of complemen- dominant 0...representative profles are shown in Fis. $-12. o -- For Nd: YAG in silicon. E, _0.99hv and the profiks are therefore and-gap recombination dominated

  3. Closure of incision in cataract surgery in-vivo using a temperature controlled laser soldering system based on a 1.9μm semiconductor laser

    NASA Astrophysics Data System (ADS)

    Gabay, Ilan; Basov, Svetlana; Varssano, David; Barequet, Irina; Rosner, Mordechai; Rattunde, Marcel; Wagner, Joachim; Platkov, Max; Harlev, Mickey; Rossman, Uri; Katzir, Abraham

    2016-03-01

    In phacoemulsification-based cataract surgery, a corneal incision is made and is then closed by hydration of the wound lips, or by suturing. We developed a system for sealing such an incision by soldering with a semiconductor disk laser (λ=1.9μm), under close temperature control. The goal was to obtain stronger and more watertight adhesion. The system was tested on incisions in the corneas of 15 eyes of pigs, in-vivo. Optical Coherent Tomography (OCT) and histopathologic examination showed little thermal damage and good apposition. The measured average burst pressure was 1000+/-30mmHg. In the future, this method wound may replace suturing of corneal wounds, including in traumatic corneal laceration and corneal transplantation.

  4. Phase Instability in Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Gil, L.; Lippi, G. L.

    2014-11-01

    For many years, the apparent absence of a phase instability has characterized lasers as peculiar nonlinear oscillators. We show that this unusual feature is solely due to the approximations used in writing the standard models. A new, careful derivation of the fundamental equations, based on codimension 2 bifurcation theory, shows the possible existence of dynamical regimes displaying either a pure phase instability, or mixed phase-amplitude turbulence. A comparison to existing experimental results convincingly shows that the Benjamin-Feir instability, common to all nonlinear wave problems, is a fundamental, satisfactory interpretation for their deterministic multimode dynamics.

  5. Photon statistics of semiconductor microcavity lasers.

    PubMed

    Ulrich, S M; Gies, C; Ates, S; Wiersig, J; Reitzenstein, S; Hofmann, C; Löffler, A; Forchel, A; Jahnke, F; Michler, P

    2007-01-26

    We present measurements of first- and second-order coherence of quantum-dot micropillar lasers together with a semiconductor laser theory. Our results show a broad threshold region for the observed high-beta microcavities. The intensity jump is accompanied by both pronounced photon intensity fluctuations and strong coherence length changes. The investigations clearly visualize a smooth transition from spontaneous to predominantly stimulated emission which becomes harder to determine for high beta. In our theory, a microscopic approach is used to incorporate the semiconductor nature of quantum dots. The results are in agreement with the experimental intensity traces and the photon statistics measurements.

  6. Whispering-gallery-mode-resonator-based ultranarrow linewidth external-cavity semiconductor laser.

    PubMed

    Liang, W; Ilchenko, V S; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L

    2010-08-15

    We demonstrate a miniature self-injection locked distributed-feedback laser using resonant optical feedback from a high-Q crystalline whispering-gallery-mode resonator. The linewidth reduction factor is greater than 10,000, with resultant instantaneous linewidth of less than 200 Hz. The minimal value of the Allan deviation for the laser-frequency stability is 3 x 10(-12) at the integration time of 20 micros. The laser possesses excellent spectral purity and good long-term stability.

  7. An efficient electron-beam-pumped semiconductor laser for the green spectral range based on II-VI multilayer nanostructures

    SciTech Connect

    Zverev, M. M.; Gamov, N. A.; Peregoudov, D. V.; Studionov, V. B.; Zdanova, E. V.; Sedova, I. V. Gronin, S. V.; Sorokin, S. V.; Ivanov, S. V.; Kop'ev, P. S.

    2008-12-15

    Emission characteristics of an electron-beam-pumped Cd(Zn)Se/ZnMgSSe semiconductor laser are studied. The laser's active region consists of a set of ten equidistant ZnSe quantum wells containing fractional-monolayer CdSe quantum-dot inserts and a waveguide formed by a short-period superlattice with the net thickness of {approx}0.65 {mu}m. Lasing occurs at room temperature at a wavelength of 542 nm. Pulsed power as high as 12 W per cavity face and an unprecedentedly high efficiency of {approx}8.5% are attained for the electron-beam energy of 23 keV.

  8. Resonance switching using ultrafast laser in THz plasmonic devices based on hybrid structure of semiconductor and carbon nanotube

    NASA Astrophysics Data System (ADS)

    Hong, J. T.; Ahn, Y. H.; Choi, S. B.; Park, D. J.

    2017-06-01

    We demonstrate all-optical switching of plasmonic resonance patterned on the carbon nanotube films supported on the silicon substrates. A considerable suppression of terahertz wave was observed in the transmission resonance, when the near-infrared femtosecond laser pulse is irradiated. A Fourier-transformed terahertz spectrum reveals that the resonance feature that was governed by the geometry of the slot antenna are almost completely removed with the laser irradiation having sufficiently high pulse energy reaching 18 μJ. A screening of terahertz field was analyzed in terms of the free carrier generation originating from the photoexcitation in semiconductor film.

  9. Injection-locked semiconductor laser-based frequency comb for modulation applications in RF analog photonics.

    PubMed

    Sarailou, Edris; Delfyett, Peter

    2016-07-01

    A linearized intensity modulator for periodic and pulsed light is proposed and demonstrated. The free carrier plasma effect has been used to modulate the refractive index of the phase section of a three-section mode-locked laser. If injection locked, the modulation induces an arcsine phase response on the three-section mode-locked laser. By introducing this mode-locked laser into a Mach-Zehnder interferometer biased at quadrature, one can realize a true linear intensity modulation. This novel laser suppresses any unwanted amplitude modulation and increases the performance of the linearized intensity modulator. Experimental results have provided a record low static Iπ of 0.39 mA and a spur-free dynamic range of 75  dB.Hz2/3.

  10. Turbulent chimeras in large semiconductor laser arrays

    PubMed Central

    Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G. P.

    2017-01-01

    Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure. PMID:28165053

  11. Turbulent chimeras in large semiconductor laser arrays

    NASA Astrophysics Data System (ADS)

    Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G. P.

    2017-02-01

    Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.

  12. Turbulent chimeras in large semiconductor laser arrays.

    PubMed

    Shena, J; Hizanidis, J; Kovanis, V; Tsironis, G P

    2017-02-06

    Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.

  13. Fiber-based multiple-beam reflection interferometer for single-longitudinal-mode generation in fiber laser based on semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Terentyev, V. S.; Simonov, V. A.; Babin, S. A.

    2017-02-01

    A technique of single-longitudinal-mode selection in a fiber laser by means of a fiber multiple-beam reflection interferometer (FRI) has been experimentally demonstrated for the first time. The laser is based on a semiconductor optical amplifier placed in a linear fiber cavity formed by a fiber Bragg grating (FBG), and the FRI generates at 1529.24 nm with output power of 1 mW in single-frequency regime with a linewidth of about 217 kHz and polarization extinction ratio of  >30 dB. The FRI technique potentially enables fast tuning (within the FBG bandwidth of ~0.9 nm in our case) by varying the base length of the FRI that can be used in a number of practical applications.

  14. Laser cooling in semiconductors (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Jun

    2017-06-01

    Laser cooling of semiconductor is very important topic in science researches and technological applications. Here we will report our progresses on laser cooling in semiconductors. By using of strong coupling between excitons and longitudinal optical phonons (LOPs), which allows the resonant annihilation of multiple LOPs in luminescence up-conversion processes, we observe a net cooling by about 40 K starting from 290 kelvin with 514-nm pumping and about 15 K starting from100 K with 532-nm pumping in a semiconductor using group-II-VI cadmium sulphide nanobelts. We also discuss the thickness dependence of laser cooing in CdS nanobelts, a concept porotype of semiconductor cryocooler and possibility of laser cooling in II-VI semiconductor family including CdSSe、CdSe, CdSe/ZnTe QDs and bulk CdS et al., Beyond II-VI semiconductor, we will present our recent progress in laser cooling of organic-inorganic perovskite materials, which show a very big cooling power and external quantum efficiency in 3D and 2D case. Further more, we demonstrate a resolved sideband Raman cooling of a specific LO phonon in ZnTe, in which only one specific phonon resonant with exciton can be cooled or heated. In the end, we will discuss the nonlinear anti-Stokes Raman and anti-Stokes photoluminescence upcoversion in very low temperature as low as down to liquid 4.2 K. In this case, the anti-Stokes resonance induces a quadratic power denpendece of anti-Stokes Raman and anti-Stokes PL. We proposed a CARS-like process to explain it. This nonlinear process also provides a possible physics picture of ultra-low temperatures phonon assisted photoluminescence and anti-Stokes Raman process.

  15. Chirp evaluation of semiconductor DFB lasers through a simple Interferometry-Based (IB) technique.

    PubMed

    Nanni, Jacopo; Barbiroli, Marina; Fuschini, Franco; Masotti, Diego; Polleux, Jean-Luc; Algani, Catherine; Tartarini, Giovanni

    2016-10-01

    Direct modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment. This paper adds a further element to the set of possible choices, since it presents a method for the evaluation of the adiabatic chirp factor in distributed feedback (DFB) laser sources, which exploits a simple interferometric scheme, guarantees low cost, and shows, at the same time, good accuracy of the results.

  16. High frequency optoelectronic oscillators based on the optical feedback of semiconductor mode-locked laser diodes.

    PubMed

    Haji, Mohsin; Hou, Lianping; Kelly, Anthony E; Akbar, Jehan; Marsh, John H; Arnold, John M; Ironside, Charles N

    2012-01-30

    Optical self seeding feedback techniques can be used to improve the noise characteristics of passively mode-locked laser diodes. External cavities such as fiber optic cables can increase the memory of the phase and subsequently improve the timing jitter. In this work, an improved optical feedback architecture is proposed using an optical fiber loop delay as a cavity extension of the mode-locked laser. We investigate the effect of the noise reduction as a function of the loop length and feedback power. The well known composite cavity technique is also implemented for suppressing supermode noise artifacts presented due to harmonic mode locking effects. Using this method, we achieve a record low radio frequency linewidth of 192 Hz for any high frequency (>1 GHz) passively mode-locked laser to date (to the best of the authors' knowledge), making it promising for the development of high frequency optoelectronic oscillators.

  17. Quantum memory node based on a semiconductor double quantum dot in a laser-controlled optical resonator

    NASA Astrophysics Data System (ADS)

    Tsukanov, A. V.; Kateev, I. Yu

    2017-08-01

    The concept of a quantum node consisting of a memory qubit and a frequency convertor is proposed and analysed. The memory qubit is presented by a semiconductor four-level double quantum dot (DQD) placed in an optical microresonator (MR). The DQD contains an electron in the quantised part of the conduction band and the MR can be populated by a certain number of photons. The DQD and MR states are controlled be applying the laser and electrostatic fields. The difference between the telecommunication frequency of the photon (transport qubit) supplied to the system through a waveguide and the frequency of the electronic transition in the DQD is compensated for using an auxiliary element, i.e. a frequency convertor based on a single quantum dot (QD). This design allows the electron – photon state of the hybrid system to be controlled by an appropriate variation of the field parameters and the switching between resonance and nonresonance DQD and MR interaction regimes. As an example, a GaAs DQD placed in a microdisk MR is studied. A numerical technique for modelling an optical spectrum of a microdisk MR with an additional layer (AL) deposited on its surface is developed. Using this technique, the effect of the AL on the MR eigenmode properties is investigated and the possibility of tuning its frequency to the QD electronic transition frequency by depositing an AL on the disk surface is demonstrated.

  18. Semiconductor Laser With Multilayer Dielectric Reflector

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1991-01-01

    Multilayer dielectric reflector included in proposed surface-emitting, distributed-feedback, grating semiconductor laser (e.g., a GaAlAs device). Contributes to efficiency and output power of laser by reducing amount of light entering substrate, where wasted by absorption. Index of refraction in reflector sublayers alternates between higher and lower value. Higher value less than effective index of refraction of waveguide layer.

  19. Broadband terahertz ultrasonic transducer based on a laser-driven piezoelectric semiconductor superlattice.

    PubMed

    Maznev, A A; Manke, Kara J; Lin, Kung-Hsuan; Nelson, Keith A; Sun, Chi-Kuang; Chyi, Jen-Inn

    2012-01-01

    Spectral characteristics of laser-generated acoustic waves in an InGaN/GaN superlattice structure are studied at room temperature. Acoustic vibrations in the structure are excited with a femtosecond laser pulse and detected via transmission of a delayed probe pulse. Seven acoustic modes of the superlattice are detected, with frequencies spanning a range from 0.36 to 2.5THz. Acoustic waves up to ∼2THz in frequency are not significantly attenuated within the transducer which indicates excellent interface quality of the superlattice. The findings hold promise for broadband THz acoustic spectroscopy.

  20. Ferromagnets based on diamond-like semiconductors GaSb, InSb, Ge, and Si supersaturated with manganese or iron impurities during laser-plasma deposition

    SciTech Connect

    Demidov, E. S.; Podol'skii, V. V.; Lesnikov, V. P.; Sapozhnikov, M. V.; Druzhnov, D. M.; Gusev, S. N.; Gribkov, B. A.; Filatov, D. O.; Stepanova, Yu. S.; Levchuk, S. A.

    2008-01-15

    Properties of thin (30-100 nm) layers of diluted magnetic semiconductors based on diamond-like compounds III-V (InSb and GaSb) and elemental semiconductors Ge and Si doped with 3d impurities of manganese and iron up to 15% were measured and discussed. The layers were grown by laser-plasma deposition onto heated single-crystal gallium arsenide or sapphire substrates. The ferromagnetism of layers with the Curie temperature up to 500 K appeared in observations of the ferromagnetic resonance, anomalous Hall effect, and magneto-optic Kerr effect. The carrier mobility of diluted magnetic semiconductors is a hundred times larger than that of the previously known highest temperature magnetic semiconductors, i.e., copper and chromium chalcogenides. The difference between changes in the magnetization with temperature in diluted semiconductors based on III-V, Ge, and Si was discussed. A complex structure of the ferromagnetic resonance spectrum in Si:Mn/GaAs was observed. The results of magnetic-force microscopy showed a weak correlation between the surface relief and magnetic inhomogeneity, which suggests that the ferromagnetism is caused by the 3d-impurity solid solution, rather than ferromagnetic phase inclusions.

  1. Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2008-05-20

    A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

  2. Method and system for powering and cooling semiconductor lasers

    DOEpatents

    Telford, Steven J; Ladran, Anthony S

    2014-02-25

    A semiconductor laser system includes a diode laser tile. The diode laser tile includes a mounting fixture having a first side and a second side opposing the first side and an array of semiconductor laser pumps coupled to the first side of the mounting fixture. The semiconductor laser system also includes an electrical pulse generator thermally coupled to the diode bar and a cooling member thermally coupled to the diode bar and the electrical pulse generator.

  3. Semiconductor Laser Linewidth Measurements for Space Interferometry Applications

    NASA Technical Reports Server (NTRS)

    Dougherty, D. J.; Guttierrez, R. C.; Dubovitsky, S.; Forouhar, S.

    2000-01-01

    Narrow linewidth (<100KHz) semiconductor lasers are expected to be a key technology in NASA's stellar interferometry missions to search for planets around nearby stars. Long coherence length lasers are needed for precise (20 pm to 5 mn) measurements of the optical path difference. This work discusses results using the self-heterodyne delay technique to measure 1.3 micrometer InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.

  4. Optically pumped semiconductor lasers for atomic and molecular physics

    NASA Astrophysics Data System (ADS)

    Burd, S.; Leibfried, D.; Wilson, A. C.; Wineland, D. J.

    2015-03-01

    Experiments in atomic, molecular and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power and intensity stability. Optically pumped semiconductor lasers (OPSLs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. We are developing a source for laser cooling and spectroscopy of Mg+ ions at 280 nm, based on a frequency quadrupled OPSL with the gain chip fabricated at the ORC at Tampere Univ. of Technology, Finland. This OPSL system could serve as a prototype for many other sources used in atomic and molecular physics.

  5. Light sources based on semiconductor current filaments

    DOEpatents

    Zutavern, Fred J.; Loubriel, Guillermo M.; Buttram, Malcolm T.; Mar, Alan; Helgeson, Wesley D.; O'Malley, Martin W.; Hjalmarson, Harold P.; Baca, Albert G.; Chow, Weng W.; Vawter, G. Allen

    2003-01-01

    The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

  6. Ultralow noise miniature external cavity semiconductor laser

    PubMed Central

    Liang, W.; Ilchenko, V. S.; Eliyahu, D.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

    2015-01-01

    Advanced applications in optical metrology demand improved lasers with high spectral purity, in form factors that are small and insensitive to environmental perturbations. While laboratory-scale lasers with extraordinarily high stability and low noise have been reported, all-integrated chip-scale devices with sub-100 Hz linewidth have not been previously demonstrated. Lasers integrated with optical microresonators as external cavities have the potential for substantial reduction of noise. However, stability and spectral purity improvements of these lasers have only been validated with rack-mounted support equipment, assembled with fibre lasers to marginally improve their noise performance. In this work we report on a realization of a heterogeneously integrated, chip-scale semiconductor laser featuring 30-Hz integral linewidth as well as sub-Hz instantaneous linewidth. PMID:26104321

  7. High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms.

    PubMed

    Santis, Christos Theodoros; Steger, Scott T; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon

    2014-02-25

    The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 μm, achieved using a single-mode silicon resonator with Q of 10(6).

  8. High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms

    PubMed Central

    Santis, Christos Theodoros; Steger, Scott T.; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon

    2014-01-01

    The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 μm, achieved using a single-mode silicon resonator with Q of 106. PMID:24516134

  9. Subwavelength metal-optic semiconductor nanopatch lasers.

    PubMed

    Yu, Kyoungsik; Lakhani, Amit; Wu, Ming C

    2010-04-26

    We report on near infrared semiconductor nanopatch lasers with subwavelength-scale physical dimensions (0.019 cubic wavelengths) and effective mode volumes (0.0017 cubic wavelengths). We observe lasing in the two most fundamental optical modes which resemble oscillating electrical and magnetic dipoles. The ultra-small laser volume is achieved with the presence of nanoscale metal patches which suppress electromagnetic radiation into free-space and convert a leaky cavity into a highly-confined subwavelength optical resonator. Such ultra-small lasers with metallodielectric cavities will enable broad applications in data storage, biological sensing, and on-chip optical communication.

  10. Integrated semiconductor twin-microdisk laser under mutually optical injection

    SciTech Connect

    Zou, Ling-Xiu; Liu, Bo-Wen; Lv, Xiao-Meng; Yang, Yue-De; Xiao, Jin-Long; Huang, Yong-Zhen

    2015-05-11

    We experimentally study the characteristics of an integrated semiconductor twin-microdisk laser under mutually optical injection through a connected optical waveguide. Based on the lasing spectra, four-wave mixing, injection locking, and period-two oscillation states are observed due to the mutually optical injection by adjusting the injected currents applied to the two microdisks. The enhanced 3 dB bandwidth is realized for the microdisk laser at the injection locking state, and photonic microwave is obtained from the electrode of the microdisk laser under the period-two oscillation state. The plentifully dynamical states similar as semiconductor lasers subject to external optical injection are realized due to strong optical interaction between the two microdisks.

  11. Alexandrite laser pumped by semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Scheps, Richard; Gately, Bernard M.; Myers, Joseph F.; Krasinski, Jerzy S.; Heller, Donald F.

    1990-06-01

    We report the first operation of a direct diode-pumped tunable chromium-doped solid-state laser. A small alexandrite (Cr:BeAl2O4) crystal was longitudinally pumped by two visible laser diodes. The threshold pump power was 12 mW using the R1 line at 680.4 nm for the pump transition, and the slope efficiency was 25%. The measured laser output bandwidth was 2.1 nm.

  12. Alexandrite laser pumped by semiconductor lasers

    SciTech Connect

    Scheps, R.; Gately, B.M.; Myers, J.F. ); Krasinski, J.S. ); Heller, D.F. )

    1990-06-04

    We report the first operation of a direct diode-pumped tunable chromium-doped solid-state laser. A small alexandrite (Cr:BeAl{sub 2}O{sub 4}) crystal was longitudinally pumped by two visible laser diodes. The threshold pump power was 12 mW using the {ital R}{sub 1} line at 680.4 nm for the pump transition, and the slope efficiency was 25%. The measured laser output bandwidth was 2.1 nm.

  13. Visible-wavelength semiconductor lasers and arrays

    DOEpatents

    Schneider, Jr., Richard P.; Crawford, Mary H.

    1996-01-01

    A visible semiconductor laser. The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1.lambda.) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%.

  14. Semiconductor ring lasers as optical neurons

    NASA Astrophysics Data System (ADS)

    Coomans, W.; Gelens, L.; Mashal, L.; Beri, S.; Van der Sande, G.; Danckaert, J.; Verschaffelt, G.

    2012-06-01

    Semiconductor Ring Lasers (SRLs) are a modern class of semiconductor lasers whose active cavity is characterized by a circular geometry. This enables the laser to support two counterpropagating modes, referred to as the clockwise (CW) and the counterclockwise (CCW) mode. Semiconductor ring lasers have been shown to have a regime of operation in which they are excitable, when the linear coupling between the counterpropagating modes is asymmetric. This can be achieved by increasing the reflection of, for example, the CW mode into the CCW mode. This will stabilize lasing in the CCW mode. In the excitable regime, the SRL will fire optical pulses (spikes) in the CW mode as a response to noise perturbations. In this contribution we experimentally and theoretically characterize these spikes. Our experiments reveal a statistical distribution of the characteristics of the optical pulses that is not observed in regular excitable systems. In particular, an inverse correlation exists between the pulse amplitude and duration. Numerical simulations and an interpretation in an asymptotic phase space confirm and explain these experimentally observed pulse characteristics [L. Gelens et al., Phys. Rev. A 82 063841, 2010]. We will also theoretically consider asymmetric SRLs coupled through a single bus waveguide. This is a first step towards an integrated optical neural network using semiconductor ring lasers as building blocks. We will show that for weak coupling, excitatory excursions still persist due to the similar phase space structure. Moreover, the coupled SRLs can excite pulses in each other and can thus function as communicating neurons [W. Coomans et al., Phys. Rev. E 84 036209, 2011]. This type of neural network can be fully integrated on chip and does not suffer from the drawback of needing extra-cavity measures, such as optical injection or saturable absorbers.

  15. Ultrafast Modulation of Semiconductor Lasers Through a Terahertz Field

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Hughes, Steven; Citrin, David

    1998-01-01

    We demonstrate, by means of numerical simulation, a new mechanism to modulate and switch semiconductor lasers at THz and sub-THz frequency rates. A sinusoidal terahertz field applied to a semiconductor laser heats the electron-hole plasma and consequently modifies the optical susceptibility. This allows an almost linear modulation of the output power of tile semiconductor laser and leads to a faithful reproduction of the terahertz-field waveform in the emitted laser intensity.

  16. Laser Cooling of 2-6 Semiconductors

    DTIC Science & Technology

    2016-08-12

    practical optical refrigeration. The challenge is the stoichiometric defect in bulk crystal which introduces mid- gap states that manifest as broad-band...which are more immune to mid- gap defects. 15. SUBJECT TERMS Laser Cooling, Optical Cooling, Bulk Semiconductors 16. SECURITY CLASSIFICATION OF: 17...stoichiometric defect in bulk crystal which introduces mid- gap states that manifest as broad-band long-wavelength emission. In this project, we have developed

  17. Optical injection in semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Coomans, W.; Beri, S.; Sande, G. Van Der; Gelens, L.; Danckaert, J.

    2010-03-01

    We theoretically investigate optical injection in semiconductor ring lasers and disclose several dynamical regimes. Through numerical simulations and bifurcation continuation, two separate parameter regions in which two different injection-locked solutions coexist are revealed, in addition to a region in which a frequency-locked limit cycle coexists with an injection-locked solution. Finally, an antiphase chaotic regime without the involvement of any carrier dynamics is revealed. Parallels are drawn with the onset of chaos in the periodically forced Duffing oscillator.

  18. Optical communication with semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic; Sun, X.

    1989-01-01

    This interim report describes the progress in the construction of a 220 Mbps Q=4 PPM optical communication system that uses a semiconductor laser as the optical transmitter and an avalanche photodiode (APD) as the photodetector. The transmitter electronics have been completed and contain both GaAs and ECL III IC's. The circuit was able to operate at a source binary data rate from 75 Mbps to 290 Mbps with pulse rise and fall times of 400 ps. The pulse shapes of the laser diode and the response from the APD/preamplifier module were also measured.

  19. High Power Continuous Wave Semiconductor Injection Laser

    DTIC Science & Technology

    1978-12-01

    hejunction rc~gion can be best accomplished in narro 7/,. laeswt width near 50 micrometers. Further optimization nnf FORM AWN2 AfI,~Jf~~’~ .* .~f’~W...high power CW operation. Trends in output powerwith varying laser length, width, reflectivity, and cavitythickness are presented graphically. LI ,N...J1 I H I I , THSI I ..... IU HIGH POWER CONTINUOUS WAVE ____________ SEMICONDUCTOR INJECTION LASER THESIS ’AIFIT/GEO/PH/78-.Z John1 C. Griffin, XIII

  20. Resonant activation in bistable semiconductor lasers

    SciTech Connect

    Lepri, Stefano; Giacomelli, Giovanni

    2007-08-15

    We theoretically investigate the possibility of observing resonant activation in the hopping dynamics of two-mode semiconductor lasers. We present a series of simulations of a rate-equation model under random and periodic modulation of the bias current. In both cases, for an optimal choice of the modulation time scale, the hopping times between the stable lasing modes attain a minimum. The simulation data are understood by means of an effective one-dimensional Langevin equation with multiplicative fluctuations. Our conclusions apply to both edge-emitting and vertical cavity lasers, thus opening the way to several experimental tests in such optical systems.

  1. Semiconductor lasers for space beacons and communications

    NASA Astrophysics Data System (ADS)

    Kung, H.; Worland, D. P.; Nguyen, H.; Streifer, W.; Scifres, D. R.

    1989-06-01

    Semiconductor lasers have been packaged and qualified for various applications in space. In this paper two subsystems are discussed, both of which will be launched shortly. The first subsystem employs a partially coherent semiconductor laser array coupled to an optical fiber, and monitored by a photo-diode.This package is used in a highly reliable, moderate data rate, moderate length communications link. The fiber coupled output power is 28 mW and the package has been fully space qualified. That is, it is free of organics, hermetically sealed, and has been subjected to die shear, acceleration, thermal cycling, and other tests. The laser longevity exceeds 10 years of continuous operation. The second subsystem consists of 27 fiber coupled space qualified packaged lasers of the same type as above, but designed to operate at 200 mW power output from the fiber. Twenty-seven fibers are bundled to produce a source with a total power emission in excess of 5 watts cw. The subsystem is part of a beacon, which will be used very shortly in a polar satellite experiment. The lasers employed in the two subsystems described above are only partially coherent and therefore are insufficiently bright to operate in a long distance, high data rate link, except with a prohibitively large lens.

  2. Semiconductor laser with the subhertz linewidth

    NASA Astrophysics Data System (ADS)

    Matveev, A. N.; Kolachevsky, N. N.; Alnis, J.; Hänsch, T. W.

    2008-10-01

    A semiconductor laser emitting at 972 nm is stabilised with respect to a vibrationally and thermally compensated reference Fabry—Perot resonator with the vertical axis. The supporting points lie in the horizontal symmetry plane of the resonator, the influence of vibrations in the vertical direction being substantially suppressed in this case. This configuration provides a low sensitivity of the laser emission frequency to vertical accelerations of the reference resonator. To reduce the influence of temperature fluctuations, the resonator is made of an ULE (ultra-low-expansion) glass and is kept at temperature at which the expansion coefficient of this glass is close to zero. The laser linewidth is smaller than 0.5 Hz and the frequency drift is ≈0.1 Hz s-1. The minimum of the Allan deviation achieved for 3 s is 2×10-15. The laser was used to record the spectra of the 1S—2S transition in atomic hydrogen.

  3. On the nonlinear theory of Fabry-Perot semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Noppe, Michael G.

    2016-05-01

    Fundamentals of the nonlinear theory of Fabry-Perot semiconductor lasers have been developed, an integral part of which is natural linewidth theory. The formula for gain depending on the energy flux specifies the basic nonlinear effect in a laser. Necessary conditions for stimulated emission of the first and second kind are presented. Maxwell’s equations in the gain medium are applied to obtain equations for energy flux and for the description of non-linear phase effect. Based on the nonlinear theory, a number of experiments have been simulated; it indicates that the nonlinear theory is a new paradigm in laser theory. The nonlinear theory has provided recommendations for the development of lasers with improved properties, such as lasers with increased power and lasers with reduced natural linewidth.

  4. Information-theoretic secure key distribution based on common random-signal induced synchronization in unidirectionally-coupled cascades of semiconductor lasers.

    PubMed

    Koizumi, Hayato; Morikatsu, Shinichiro; Aida, Hiroki; Nozawa, Takahiro; Kakesu, Izumi; Uchida, Atsushi; Yoshimura, Kazuyuki; Muramatsu, Jun; Davis, Peter

    2013-07-29

    It has been proposed that a secure key distribution scheme using correlated random bit sequences can be implemented using common random-signal induced synchronization of semiconductor laser systems. In this scheme it is necessary to use laser systems consisting of multiple cascaded lasers to be secure against a powerful eavesdropper. In this paper, we report the results of an experimental study that demonstrate that the common random-signal induced synchronization is possible in cascaded semiconductor laser systems. We also show that the correlated random bit sequences generated in the synchronized cascaded laser systems can be used to create an information-theoretically secure key between two legitimate users.

  5. Electrically pumped edge-emitting photonic bandgap semiconductor laser

    DOEpatents

    Lin, Shawn-Yu; Zubrzycki, Walter J.

    2004-01-06

    A highly efficient, electrically pumped edge-emitting semiconductor laser based on a one- or two-dimensional photonic bandgap (PBG) structure is described. The laser optical cavity is formed using a pair of PBG mirrors operating in the photonic band gap regime. Transverse confinement is achieved by surrounding an active semiconductor layer of high refractive index with lower-index cladding layers. The cladding layers can be electrically insulating in the passive PBG mirror and waveguide regions with a small conducting aperture for efficient channeling of the injection pump current into the active region. The active layer can comprise a quantum well structure. The quantum well structure can be relaxed in the passive regions to provide efficient extraction of laser light from the active region.

  6. Use of a semiconductor diode laser in laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Sakr, Ghazi; Watson, Graham M.; Lawrence, William

    1996-05-01

    The gold standard surgical treatment of benign prostatic hyperplasia (BPH) is transurethral resection of the prostate (TURP). Over the past few years, TURP has been challenged by laser prostatectomy, a technique that offered many advantages including minimal bleeding, short hospital stay, no fluid absorption, rapid learning curve and better change to preserve antegrade ejaculation. Laser prostatectomy can be done by vaporizing or coagulating prostatic tissue and more recently by using a combination of both: The hybrid technique Nd:YAG lasers have been used, (coupled with contact tips or with side firing or even bare fibers) to either coagulate or vaporize prostatic tissue. Recently semiconductor diode lasers have become available and offer certain advantages. They are compact portable units with no need for water cooling, yet they have sufficient power for tissue vaporization. Diomed (Cambridge, U.K.), produces a 60 W gallium aluminum arsenide semiconductor diode laser emitting at 810 nm. We report the first clinical experience using a semiconductor diode laser for prostates using a combination of contact tip and sidefiring.

  7. Gain coupling of class A semiconductor lasers.

    PubMed

    Hessenius, Chris; Terry, Nathan; Fallahi, Mahmoud; Moloney, Jerome; Bedford, Robert

    2010-09-15

    We report on the development of a gain-coupled class A semiconductor laser for dual-wavelength generation via optical switching. A vertical external cavity surface emitting laser (VECSEL) structure is used, because it provides a flexible platform for high-power, high-brightness output in the near-IR and visible ranges. For the first time (to our knowledge), two VECSEL cavities sharing a common gain region are studied. Because the cavities are in competition for common carriers, birefringent filters in the external cavity control the laser cavity thresholds; this configuration demonstrates the possibility of switching between the two cavities, which can operate at different wavelengths. However, in this Letter we also show, numerically and experimentally, that with the consideration of spontaneous emission, it is possible to maintain simultaneous lasing in each cavity at a different wavelength.

  8. Approaches toward a blue semiconductor laser

    NASA Technical Reports Server (NTRS)

    Ladany, I.

    1989-01-01

    Possible approaches for obtaining semiconductor diode laser action in the blue region of the spectrum are surveyed. A discussion of diode lasers is included along with a review of the current status of visible emitters, presently limited to 670 nm. Methods are discussed for shifting laser emission toward shorter wavelengths, including the use of II-IV materials, the increase in the bandgap of III-V materials by addition of nitrogen, and changing the bandstructure from indirect to direct by incorporating interstitial atoms or by constructing superlattices. Non-pn-junction injection methods are surveyed, including avalanche breakdown, Langmuir-Blodgett diodes, heterostructures, carrier accumulation, and Berglund diodes. Prospects of inventing new multinary semiconducting materials are discussed, and a number of novel materials described in the literature are tabulated. New approaches available through the development of quantum wells and superlattices are described, including resonant tunneling and the synthesis of arbitrary bandgap materials through multiple quantum wells.

  9. Semiconductor disk laser pumped Cr2+:Znse lasers.

    PubMed

    Hempler, Nils; Hopkins, John-Mark; Rösener, Benno; Rattunde, Marcel; Wagner, Joachim; Fedorov, Vladimir V; Moskalev, Igor S; Mirov, Sergey B; Burns, David

    2009-09-28

    A new flexible pump source, the optically-pumped semiconductor disk laser (SDL), for the Cr(2+):ZnSe laser is reported. The SDL provides up to 6W output power at a free running central wavelength of 1.98 microm. The Cr(2+):ZnSe laser operated at an output power of 1.8W and a slope efficiency of approximately 50% with respect to absorbed pump power whilst maintaining a low output intensity noise figure of <0.14% RMS. The system required no optical isolation even under the situation of significant optical feedback.

  10. Timing and amplitude jitter in a gain-switched multimode semiconductor laser

    NASA Astrophysics Data System (ADS)

    Wada, Kenji; Kitagawa, Naoaki; Matsukura, Satoru; Matsuyama, Tetsuya; Horinaka, Hiromichi

    2016-04-01

    The differences in timing jitter between a gain-switched single-mode semiconductor laser and a gain-switched multimode semiconductor laser are examined using rate equations that include Langevin noise. The timing jitter in a gain-switched multimode semiconductor laser is found to be effectively suppressed by a decrease in the coherence time of the amplified spontaneous emission (ASE) based on a broad bandwidth of multimode oscillation. Instead, fluctuations in the ASE cause amplitude jitter in the pulse components of the respective modes. A pulse train of gain-switched pulses from a multimode semiconductor laser with timing jitter is equivalently simulated by assuming a high spontaneous emission factor and a short coherence time of the ASE in the single-mode semiconductor laser rate equations.

  11. Optical-cell model based on the lasing competition of mode structures with different Q-factors in high-power semiconductor lasers

    SciTech Connect

    Podoskin, A. A. Shashkin, I. S.; Slipchenko, S. O.; Pikhtin, N. A.; Tarasov, I. S.

    2015-08-15

    A model describing the operation of a completely optical cell, based on the competition of lasing of Fabry-Perot cavity modes and the high-Q closed mode in high-power semiconductor lasers is proposed. Based on rate equations, the conditions of lasing switching between Fabry-Perot modes for ground and excited lasing levels and the closed mode are considered in the case of increasing internal optical loss under conditions of high current pump levels. The optical-cell operation conditions in the mode of a high-power laser radiation switch (reversible mode-structure switching) and in the mode of a memory cell with bistable irreversible lasing switching between mode structures with various Q-factors are considered.

  12. Self-collimated unstable resonator semiconductor laser

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1993-01-01

    Self-collimation of the output is achieved in an unstable resonator semiconductor laser by providing a large concave mirror M sub 1 and a small convex mirror M sub 2 on opposite surfaces of a semiconductor body of a material having an effective index of refraction denoted by n, where the respective mirror radii R sub 1, R sub 2 and beam radii r sub 1, r sub 2 are chosen to satisfy a condition (R sub 2)/(1 + r sub 1) = (n - 1)/n, with a value of geometric magnification 1 less than or equal to M less than or equal to (n + 1)/(n - 1) where r sub 1 and r sub 2 are the radii of counterpropagating beams at respective mirrors of radii R sub 1 and R sub 2.

  13. Semiconductor Lasers Containing Quantum Wells in Junctions

    NASA Technical Reports Server (NTRS)

    Yang, Rui Q.; Qiu, Yueming

    2004-01-01

    In a recent improvement upon In(x)Ga(1-x)As/InP semiconductor lasers of the bipolar cascade type, quantum wells are added to Esaki tunnel junctions, which are standard parts of such lasers. The energy depths and the geometric locations and thicknesses of the wells are tailored to exploit quantum tunneling such that, as described below, electrical resistances of junctions and concentrations of dopants can be reduced while laser performances can be improved. In(x)Ga(1-x)As/InP bipolar cascade lasers have been investigated as sources of near-infrared radiation (specifically, at wavelengths of about 980 and 1,550 nm) for photonic communication systems. The Esaki tunnel junctions in these lasers have been used to connect adjacent cascade stages and to enable transport of charge carriers between them. Typically, large concentrations of both n (electron-donor) and p (electron-acceptor) dopants have been necessary to impart low electrical resistances to Esaki tunnel junctions. Unfortunately, high doping contributes free-carrier absorption, thereby contributing to optical loss and thereby, further, degrading laser performance. In accordance with the present innovation, quantum wells are incorporated into the Esaki tunnel junctions so that the effective heights of barriers to quantum tunneling are reduced (see figure).

  14. Visible-wavelength semiconductor lasers and arrays

    DOEpatents

    Schneider, R.P. Jr.; Crawford, M.H.

    1996-09-17

    The visible semiconductor laser includes an InAlGaP active region surrounded by one or more AlGaAs layers on each side, with carbon as the sole p-type dopant. Embodiments of the invention are provided as vertical-cavity surface-emitting lasers (VCSELs) and as edge-emitting lasers (EELs). One or more transition layers comprised of a substantially indium-free semiconductor alloy such as AlAsP, AlGaAsP, or the like may be provided between the InAlGaP active region and the AlGaAS DBR mirrors or confinement layers to improve carrier injection and device efficiency by reducing any band offsets. Visible VCSEL devices fabricated according to the invention with a one-wavelength-thick (1{lambda}) optical cavity operate continuous-wave (cw) with lasing output powers up to 8 mW, and a peak power conversion efficiency of up to 11%. 5 figs.

  15. Thermal runaway in semiconductor laser windows.

    PubMed

    Johnson, R L; O'Keefe, J D

    1972-12-01

    A small perturbation model is used to obtain analytical expressions for the critical or runaway power density for laser windows constructed of semiconductor materials. These equations are used to compute the critical power density for several realistic window installations taking account of the finite value of realizable convection cooling coefficients. Computations were prepared for silicon transmitting 4 .0-micro. radiation and for germanium at 10.6 micro. In this way it is shown that power densities are principally limited by the effectiveness of cooling from the face of the window, that is, the surface perpendicular to the laser beam. Since convection cooling coefficients are small the transmission of high power densities through semiconductor windows is therefore contingent upon finding more effective means to cool the window from the face. Finally, a simplified calculation was made in an attempt to account for nonuniformity of the incident laser beam. a given window, but not severely. The results show the onuniformity reduces the runaway power for a given window, but not severely.

  16. Semiconductor Nanomaterials-Based Fluorescence Spectroscopic and Matrix-Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometric Approaches to Proteome Analysis

    PubMed Central

    Kailasa, Suresh Kumar; Cheng, Kuang-Hung; Wu, Hui-Fen

    2013-01-01

    Semiconductor quantum dots (QDs) or nanoparticles (NPs) exhibit very unusual physico-chemcial and optical properties. This review article introduces the applications of semiconductor nanomaterials (NMs) in fluorescence spectroscopy and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for biomolecule analysis. Due to their unique physico-chemical and optical properties, semiconductors NMs have created many new platforms for investigating biomolecular structures and information in modern biology. These semiconductor NMs served as effective fluorescent probes for sensing proteins and cells and acted as affinity or concentrating probes for enriching peptides, proteins and bacteria proteins prior to MALDI-MS analysis. PMID:28788422

  17. Semiconductor lasers for versatile applications from global communications to on-chip interconnects

    NASA Astrophysics Data System (ADS)

    Arai, Shigehisa

    2015-01-01

    Since semiconductor lasers were realized in 1962, various efforts have been made to enrich human life thorough novel equipments and services. Among them optical fiber communications in global communications have brought out marvelous information technology age represented by the internet. In this paper, emerging topics made on GaInAsP/InP based long-wavelength lasers toward ultra-low power consumption semiconductor lasers for optical interconnects in supercomputers as well as in future LSIs are presented.

  18. Generation of high-peak-power sub-nanosecond 650-nm-band optical pulses based on semiconductor-laser-controlling technologies

    NASA Astrophysics Data System (ADS)

    Hung, Jui-Hung; Sato, Kazuo; Fang, Yi-Cheng; Peng, Lung-Han; Nemoto, Tomomi; Yokoyama, Hiroyuki

    2017-10-01

    We have developed a method to generate sub-nanosecond 650-nm-band optical pulses. These pulses have a peak power of 40 W and a pulse energy of 13 nJ at a 1-MHz repetition rate. This technology is intended for application in stimulated-emission-depletion microscopy. Our method is based on the pulsed operation of a 1.3-µm-band semiconductor-laser optical amplifier and the second-harmonic generation of the optical pulses after amplification by a Pr-doped fiber amplifier. The resultant peak power and pulse energy of the 650-nm-band optical pulses are two orders of magnitude higher than those directly obtained from a laser diode.

  19. Multiphoton in vivo imaging with a femtosecond semiconductor disk laser

    PubMed Central

    Voigt, Fabian F.; Emaury, Florian; Bethge, Philipp; Waldburger, Dominik; Link, Sandro M.; Carta, Stefano; van der Bourg, Alexander; Helmchen, Fritjof; Keller, Ursula

    2017-01-01

    We use an ultrafast diode-pumped semiconductor disk laser (SDL) to demonstrate several applications in multiphoton microscopy. The ultrafast SDL is based on an optically pumped Vertical External Cavity Surface Emitting Laser (VECSEL) passively mode-locked with a semiconductor saturable absorber mirror (SESAM) and generates 170-fs pulses at a center wavelength of 1027 nm with a repetition rate of 1.63 GHz. We demonstrate the suitability of this laser for structural and functional multiphoton in vivo imaging in both Drosophila larvae and mice for a variety of fluorophores (including mKate2, tdTomato, Texas Red, OGB-1, and R-CaMP1.07) and for endogenous second-harmonic generation in muscle cell sarcomeres. We can demonstrate equivalent signal levels compared to a standard 80-MHz Ti:Sapphire laser when we increase the average power by a factor of 4.5 as predicted by theory. In addition, we compare the bleaching properties of both laser systems in fixed Drosophila larvae and find similar bleaching kinetics despite the large difference in pulse repetition rates. Our results highlight the great potential of ultrafast diode-pumped SDLs for creating a cost-efficient and compact alternative light source compared to standard Ti:Sapphire lasers for multiphoton imaging. PMID:28717563

  20. Power semiconductor laser diode arrays characterization

    NASA Astrophysics Data System (ADS)

    Zeni, Luigi; Campopiano, Stefania; Cutolo, Antonello; D'Angelo, Giuseppe

    2003-09-01

    Nowadays, power semiconductor laser diode arrays are becoming a widespread source for a large variety of industrial applications. In particular, the availability of low-cost high-power laser diode arrays makes their use possible in the industrial context for material cutting, welding, diagnostics and processing. In the above applications, the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. In this paper, we present two different approaches useful for the characterization of the beam quality in laser diode arrays. The first one, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The second one is aimed at the measurement of a global quality factor of the array itself; to this end, the empirical extension of the M2 concept to composite beams is presented along with some experimental results. As the first technique is especially intended for the non-destructive detection of design problems in the array itself and in the bias circuitry, the second one represents a powerful tool for the rapid on-line diagnostics of the laser beam during its use.

  1. Subwavelength Nanopatch Cavities for Semiconductor Plasmon Lasers

    NASA Astrophysics Data System (ADS)

    Manolatou, Christina; Rana, Farhan

    2008-05-01

    We propose and analyze a family of nanoscale cavities for electrically-pumped surface-emitting semiconductor lasers that use surface plasmons to provide optical mode confinement in cavities which have dimensions in the 100-300 nm range. The proposed laser cavities are in many ways nanoscale optical versions of micropatch antennas that are commonly used at microwave/RF frequencies. Surface plasmons are not only used for mode confinement but also for output beam shaping to realize single-lobe far-field radiation patterns with narrow beam waists from subwavelength size cavities. We identify the cavity modes with the largest quality factors and modal gain, and show that in the near-IR wavelength range (1.0-1.6 microns) cavity losses (including surface plasmon losses) can be compensated by the strong mode confinement in the gain region provided by the surface plasmons themselves and the required material threshold gain values can be smaller than 700 1/cm.

  2. Widely tunable coupled-cavity semiconductor laser.

    PubMed

    Khan, Ferdous K; Cassidy, Daniel T

    2009-07-01

    We describe a widely tunable coupled-cavity semiconductor laser with a nearly continuous tuning capability of approximately 100 nm. A below threshold model for coupled-cavity devices using a transfer matrix approach that takes into account the tilt of the facets forming the gap between the coupled sections was developed and is presented. Nonlinear fits of the below-threshold spectra to the model were used to extract device parameters. These fits and parameters were then used to understand the operation of the devices and the direction to take to improve the performance of the devices. It is observed that for facet angles > or = 7 degrees, a two-section coupled-cavity device works like an injection-locked laser, while for angles < or = 4 degrees, the sections work as a truly-coupled system.

  3. Self-mode-locking semiconductor disk laser.

    PubMed

    Gaafar, Mahmoud; Richter, Philipp; Keskin, Hakan; Möller, Christoph; Wichmann, Matthias; Stolz, Wolfgang; Rahimi-Iman, Arash; Koch, Martin

    2014-11-17

    The development of mode-locked semiconductor disk lasers received striking attention in the last 14 years and there is still a vast potential of such pulsed lasers to be explored and exploited. While for more than one decade pulsed operation was strongly linked to the employment of a saturable absorber, self-mode-locking emerged recently as an effective and novel technique in this field - giving prospect to a reduced complexity and improved cost-efficiency of such lasers. In this work, we highlight recent achievements regarding self-mode-locked semiconductor devices. It is worth to note, that although nonlinear effects in the active medium are expected to give rise to self-mode-locking, this has to be investigated with care in future experiments. However, there is a controversy whether results presented with respect to self-mode-locking truly show mode-locking. Such concerns are addressed in this work and we provide a clear evidence of mode-locking in a saturable-absorber-free device. By using a BBO crystal outside the cavity, green light originating from second-harmonic generation using the out-coupled laser beam is demonstrated. In addition, long-time-span pulse trains as well as radiofrequency-spectra measurements are presented for our sub-ps pulses at 500 MHz repetition rate which indicate the stable pulse operation of our device. Furthermore, a long-time-span autocorrelation trace is introduced which clearly shows absence of a pedestal or double pulses. Eventually, a beam-profile measurement reveals the excellent beam quality of our device with an M-square factor of less than 1.1 for both axes, showing that self-mode-locking can be achieved for the fundamental transverse mode.

  4. Modulation Effects in Multi-Section Semiconductor Lasers (Postprint)

    DTIC Science & Technology

    2013-01-01

    resonant modulation of semiconductor lasers beyond relaxation oscillation frequency,” Appl. Phys. Lett., 63, 1459–1461 (1993). [26] J. Helms and K. Petermann ...5, 4–6 (1993). [28] K. Petermann , “External optical feedback phenomena in semiconductor lasers,” IEEE J. Sel. Top. Quantum Elec- tron., 1, 480–489

  5. High power mode-locked semiconductor lasers and their applications

    NASA Astrophysics Data System (ADS)

    Lee, Shinwook

    In this dissertation, a novel semiconductor mode-locked oscillator which is an extension of eXtreme Chirped Pulse Amplification (XCPA) is investigated. An eXtreme Chirped Pulse Oscillator (XCPO) implemented with a Theta cavity also based on a semiconductor gain is presented for generating more than 30ns frequency-swept pulses with more than 100pJ of pulse energy and 3.6ps compressed pulses directly from the oscillator. The XCPO shows the two distinct characteristics which are the scalability of the output energy and the mode-locked spectrum with respect to repetition rate. The laser cavity design allows for low repetition rate operation <100MHz. The cavity significantly reduces nonlinear carrier dynamics, integrated self phase modulation (SPM), and fast gain recovery in a Semiconductor optical Amplifier (SOA). Secondly, a functional device, called a Grating Coupled Surface Emitting Laser (GCSEL) is investigated. For the first time, passive and hybrid mode-locking of a GCSEL is achieved by using saturable absorption in the passive section of GCSEL. To verify the present limitation of the GCSEL for passive and hybrid mode-locking, a dispersion matched cavity is explored. In addition, a Grating Coupled surface emitting Semiconductor Optical Amplifier (GCSOA) is also investigated to achieve high energy pulse. An energy extraction experiment for GCSOA using stretched pulses generated from the colliding pulse semiconductor mode-locked laser via a chirped fiber bragg grating, which exploits the XCPA advantages is also demonstrated. Finally, passive optical cavity amplification using an enhancement cavity is presented. In order to achieve the interferometric stability, the Hansch-Couillaud Method is employed to stabilize the passive optical cavity. The astigmatism-free optical cavity employing an acoustov optic modulator (AOM) is designed and demonstrated. In the passive optical cavity, a 7.2 of amplification factor is achieved with a 50 KHz dumping rate.

  6. Laser cooling of a semiconductor by 40 kelvin.

    PubMed

    Zhang, Jun; Li, Dehui; Chen, Renjie; Xiong, Qihua

    2013-01-24

    absorption. Our findings suggest that, alternatively, group-II-VI semiconductors with strong exciton-LOP coupling could be harnessed to achieve laser cooling and open the way to optical refrigeration based on semiconductors.

  7. Electron circuits: Semiconductor laser multiple use installation

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Fan, J.; Weng, D.

    1983-04-01

    A light source for a multiple use installation using a same matter junction or different matter junction GaAlAs/GaAs semiconductor laser, which has the advantages of high interference resistance, long transmission distance (tens to hundreds of meters), good security, and low power consumption; in addition, the controller of the light source has multiple usages of alarming, switching and counting is presented. The multiple use installation can be used in control of breaking warps and counting on roving waste machines, warping machines and silk weaving machines in the textile industry; long distance speed measurement, alarming and counting in machinery, electricity and chemical industries; and alarming and control of water levels in reservoirs, rivers and water towers, as well as blockade alarming and control of important divisions. This multiple use installation is composed of two parts a laser emitter and a receiving device. The former component is used to produce the laser; after the receiver receives the laser, the installation completes operations of alarming, switching and counting.

  8. Phase-Locked Semiconductor Lasers With Separate Contacts

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Yariv, Amnon; Margalit, Shlomo

    1988-01-01

    Individual current feeds enable better uniformity and flexible control. Separate contacts for lasers in array enable control of output radiation pattern and compensation of manufacturing nonuniformities among lasers. Concept of separate current control described for two-laser array in "Semiconductor Laser Phased Array" (NPO-15963).

  9. Ferromagnet/semiconductor based spintronic devices

    NASA Astrophysics Data System (ADS)

    Saha, Dipankar

    Spintronics is an emerging field which is great interest for its potential to provide high-speed and low-power novel devices and eventually replace and/or complement conventional silicon-based metal-oxide-semiconductor (MOS) devices. Spin-based optoelectronic devices provide improved laser performance and polarized light sources for secure communication. Spintronics has therefore received a lot of interest with the potential for conventional and novel applications. Spintronics has been investigated both in all-metal and semiconductor based platforms. Spin-based ferromagnet/semiconductor heterojunction devices are particularly attractive compared to all-metal spintronic devices due to the versatility and the long electron spin coherence time in semiconductors. Here we have investigated semiconductor based spintronic devices for logic, memory and communication applications. We have demonstrated electrical injection and detection of spin in a MnAs/GaAs lateral spin valve. A peak magnetoresistance of 3.6% at 10 K and 1.1% at 125 K have been measured in these devices. Spin polarization in semiconductors is usually very small and difficult to detect. We have therefore theoretically designed and experimentally demonstrated a spin-current amplifier to alleviate this problem. A spin polarization of 100% has been measured at 150 K in these devices. We have emphasized the importance of finite sizes of ferromagnetic contact pads in terms of two-dimensional spin-diffusion in lateral spintronic devices, which enhances spin-polarization. We have discovered a new phenomenon observing electrically driven spin-dynamics of paramagnetic impurities. We have demonstrated a spin-capacitor using this novel phenomenon. In this study we have also demonstrated a spin-polarized quantum dot spin-laser which is a fundamental spin-based optoelectronic device. An output circular polarization of 8% and threshold current reduction of 14% have been measured at 200 K. We have also demonstrated

  10. Modes in light wave propagating in semiconductor laser

    NASA Technical Reports Server (NTRS)

    Manko, Margarita A.

    1994-01-01

    The study of semiconductor laser based on an analogy of the Schrodinger equation and an equation describing light wave propagation in nonhomogeneous medium is developed. The active region of semiconductor laser is considered as optical waveguide confining the electromagnetic field in the cross-section (x,y) and allowing waveguide propagation along the laser resonator (z). The mode structure is investigated taking into account the transversal and what is the important part of the suggested consideration longitudinal nonhomogeneity of the optical waveguide. It is shown that the Gaussian modes in the case correspond to spatial squeezing and correlation. Spatially squeezed two-mode structure of nonhomogeneous optical waveguide is given explicitly. Distribution of light among the laser discrete modes is presented. Properties of the spatially squeezed two-mode field are described. The analog of Franck-Condon principle for finding the maxima of the distribution function and the analog of Ramsauer effect for control of spatial distribution of laser emission are discussed.

  11. Transient thermal analysis of semiconductor diode lasers under pulsed operation

    NASA Astrophysics Data System (ADS)

    Veerabathran, G. K.; Sprengel, S.; Karl, S.; Andrejew, A.; Schmeiduch, H.; Amann, M.-C.

    2017-02-01

    Self-heating in semiconductor lasers is often assumed negligible during pulsed operation, provided the pulses are `short'. However, there is no consensus on the upper limit of pulse width for a given device to avoid-self heating. In this paper, we present an experimental and theoretical analysis of the effect of pulse width on laser characteristics. First, a measurement method is introduced to study thermal transients of edge-emitting lasers during pulsed operation. This method can also be applied to lasers that do not operate in continuous-wave mode. Secondly, an analytical thermal model is presented which is used to fit the experimental data to extract important parameters for thermal analysis. Although commercial numerical tools are available for such transient analyses, this model is more suitable for parameter extraction due to its analytical nature. Thirdly, to validate this approach, it was used to study a GaSb-based inter-band laser and an InP-based quantum cascade laser (QCL). The maximum pulse-width for less than 5% error in the measured threshold currents was determined to be 200 and 25 ns for the GaSb-based laser and QCL, respectively.

  12. Multi-spectral imaging with mid-infrared semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Wang, Yang; Le, Han Q.

    2006-01-01

    Multi-spectral laser imaging can be a useful technology for target discrimination, classification, and identification based on object spectral signatures. The mid-IR region (~3-14 μm) is particularly rich of molecular spectroscopic fingerprints, but the technology has been under utilized. Compact, potentially inexpensive semiconductor lasers may allow more cost-effective applications. This paper describes a development of semiconductor-laser-based multi-spectral imaging for both near-IR and mid-IR, and demonstrates the potential of this technology. The near-IR study employed 7 wavelengths from 0.635-1.55 μm, and used for system engineering evaluation as well as for studying the fundamental aspects of multi-spectral laser imaging. These include issues of wavelength-dependence scattering as a function of incident and receiving angle and the polarization effects. Stokes vector imaging and degree-of-linear-polarization were shown to reveal significant information to characterize the targets. The mid-IR study employed 4 wavelengths from 3.3-9.6 μm, and was applied to diverse targets that consist of natural and man-made materials and household objects. It was shown capable to resolve and distinguish small spectral differences among various targets, thanks to the laser radiometric and spectral accuracy. Colorless objects in the visible were shown with "colorful" signatures in the mid-IR. An essential feature of the study is an advanced system architecture that employs wavelength-division-multiplexed laser beams for high spectral fidelity and resolution. In addition, unlike conventional one-transmitter and one receiver design, the system is based on a scalable CDMA network concept with multiple transmitters and receivers to allow efficient information acquisition. The results suggest that multi-spectral laser imaging in general can be a unique and powerful technology for wide ranging applications.

  13. Semiconductor single crystal external ring resonator cavity laser and gyroscope

    SciTech Connect

    Spitzer, M.P.

    1993-08-31

    A ring laser is described comprising: a semiconductor single crystal external ring resonator cavity having a plurality of reflecting surfaces defined by the planes of the crystal and establishing a closed optical path; and a discrete laser medium disposed in said semiconductor single crystal external ring resonator cavity for generating coherent light in said cavity, wherein said resonator cavity is decoupled from the laser medium.

  14. Laser micromachining of semiconductors for photonics applications

    NASA Astrophysics Data System (ADS)

    Nantel, Marc; Yashkir, Yuri; Lee, Seong K.; Mugford, Chas; Hockley, Bernard S.

    2001-10-01

    For decades, precisely machining silicon has been critical for the success of the semiconductor industry. This has traditionally been done through wet chemical etching, but in the pursuit of integrating photonics devices on a single chip, other techniques are worth exploring. This quest opens up interest in finding a non-wet, non-contact, arbitrary-shape milling technique for silicon. In this paper, we present our latest work in the laser micromachining of silicon. A kilohertz-repetition-rate diode-pumped Nd:YLF laser (in infrared, green or ultraviolet modes) is focused on the surface of silicon wafers in a chlorine atmosphere for an enhanced magnitude and control of the etching rate. In the chlorine atmosphere, much less debris is deposited on the surface around the cut, sub-damage threshold machining is achieved for a better control of the etching depth, and etching rates ranging from 20-300,000 micron-cube/s have been measured. In particular, the use of an infrared laser beam is singled out, along with the advantages that it holds. Results of simulations highlight the particular characteristics of the various wavelength chosen for the machining.

  15. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum

    PubMed Central

    Seghilani, Mohamed S.; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-01-01

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here “orbital birefringence”, based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create “orbital gain dichroism” allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications. PMID:27917885

  16. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Seghilani, Mohamed S.; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-12-01

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here “orbital birefringence”, based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create “orbital gain dichroism” allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications.

  17. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum.

    PubMed

    Seghilani, Mohamed S; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-12-05

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here "orbital birefringence", based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create "orbital gain dichroism" allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications.

  18. Photon number squeezed states in semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Yamamoto, Yoshihisa; Machida, Susumu; Richardson, Wayne H.

    1992-01-01

    Electromagnetic fields, with the noise on one quadrature component reduced to below the quantum mechanical zero-point fluctuation level and the noise on the other quadrature component enhanced to above it, are currently of great interest in quantum optics because of their potential applications to various precision measurements. Such squeezed states of light are usually produced by imposing nonlinear unitary evolution on coherent (or vacuum) states. On the other hand, squeezed states with reduced photon number noise and enhanced phase noise are generated directly by a constant current-driven semiconductor laser. This is the simplest scheme for the generation of nonclassical light, and so far it has yielded the largest quantum noise reduction. The mutual coupling between a lasing junction and an external electrical circuit provides opportunities for exploring the macroscopic and microscopic quantum effects in open systems.

  19. Mode beating and heterodyning of monolithically integrated semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Liu, Chiyu

    Monolithically integrated semiconductor ring lasers (SRLs) are attractive optical sources for optoelectronic integrated circuits (OEICs) because they do not require any feedback elements, do not have parts exposed to external ambient, and can operate in a traveling-wave mode. They are promising candidates for wavelength filtering, unidirectional traveling-wave operation, and multiplexing/demultiplexing applications. Ring lasers can also be used as ultrashort pulse generators using various mode-locking schemes and as active gyro components. However, the SRL is a very complicated dynamic system, which requires more investigations to understand the performance regarding details of the design and fabrication. As a part of NASA-supported project "Monolithically Integrated Semiconductor Ring Laser Gyro for Space Applications", this dissertation research was focused on design and characterization of a novel monolithically integrated rotation sensor based on two large-size independent SRLs. Numerical modeling based on the beam propagation method (BPM) was used to design the fabrication parameters for the single-mode ridge-waveguide ring cavity and directional coupler waveguides. The mode internal coupling in single lateral-mode laser diodes with InGaAs/GaAs material system was investigated by optical experiments and numerical modeling. To gain the understanding of the SRL performance, optical and electrical characterization was performed on fabricated SRLs. Particular emphasis was placed on the study of optical and radio frequency (RF) beating spectra of longitudinal modes of ring lasers. RF measurements provide high accuracy in the diagnosis of laser oscillation parameters by purely electronic means, particularly in the measurement of the group index and its dependence on current and temperature. Theoretical analysis based on the effective index method provides good agreement between the experimental data and numerical calculations. Finally, optical heterodyning spectra

  20. Suppression of phase and supermode noise in a harmonic mode-locked erbium-doped fiber laser with a semiconductor-optical-amplifier-based high-pass filter.

    PubMed

    Lin, Gong-Ru; Wu, Ming-Chung; Chang, Yung-Cheng

    2005-07-15

    By operating an intracavity semiconductor-optical-amplifier- (SOA-) based high-pass filter at the nearly transparent current condition, the supermode noise (SMN), the relaxation oscillation, and the single-sideband (SSB) phase noise can be simultaneously suppressed in an actively mode-locked erbium-doped fiber laser (EDFL). The SOA at the nearly transparent condition enhances the SMN suppression ratio of the EDFL from 32 to 76 dB at the cost of the phase noise degrading from -114 to -104.2 dBc/Hz and broadening the pulse width from 36 to 61 ps. With an optical bandpass filter, the SSB phase noise and the SMN suppression ratio can be further improved to -110 dBc/Hz and 81 dB, respectively. The EDFL pulse can be further shortened to 3.1 ps with a time-bandwidth product of 0.63 after compression.

  1. Frequency-stabilised external-cavity semiconductor laser

    SciTech Connect

    Permyakova, O I; Yakovlev, A V; Chapovskii, Pavel L

    2005-05-31

    The design and characteristics of a semiconductor laser with the modified external Littrow resonator are described. The additional output mirror of the V-shaped resonator made the system more efficient and convenient. The laser radiation frequency is stabilised with the help of magnetooptical Faraday and circular dichroism effects in rubidium vapour. (diode lasers)

  2. Monolayer semiconductor nanocavity lasers with ultralow thresholds.

    PubMed

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R; Feng, Liefeng; Yan, Jiaqiang; Mandrus, David G; Hatami, Fariba; Yao, Wang; Vučković, Jelena; Majumdar, Arka; Xu, Xiaodong

    2015-04-02

    Engineering the electromagnetic environment of a nanometre-scale light emitter by use of a photonic cavity can significantly enhance its spontaneous emission rate, through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter, providing a low-threshold laser system with small footprint, low power consumption and ultrafast modulation. An ultralow-threshold nanoscale laser has been successfully developed by embedding quantum dots into a photonic crystal cavity (PCC). However, several challenges impede the practical application of this architecture, including the random positions and compositional fluctuations of the dots, extreme difficulty in current injection, and lack of compatibility with electronic circuits. Here we report a new lasing strategy: an atomically thin crystalline semiconductor--that is, a tungsten diselenide monolayer--is non-destructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PCC. A continuous-wave nanolaser operating in the visible regime is thereby achieved with an optical pumping threshold as low as 27 nanowatts at 130 kelvin, similar to the value achieved in quantum-dot PCC lasers. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within one nanometre of the PCC surface. The surface-gain geometry gives unprecedented accessibility and hence the ability to tailor gain properties via external controls such as electrostatic gating and current injection, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.

  3. Metal-oxide-semiconductor plasmonic nanorod lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Gwo, Shangjr

    2017-02-01

    Scaling down semiconductor lasers in all three dimensions hold the key to the developments of compact, low-threshold, and ultrafast coherent light sources, as well as photonic integrated circuits. However, the minimum size of conventional semiconductor lasers utilizing dielectric cavity resonators (photonic cavities) is constrained to the diffraction limit. In the past few years, it has been experimentally demonstrated that the use of plasmonic cavities based on metal-oxide-semiconductor (MOS) structures can break this limit. In this presentation, I will report on the recent progress of plasmonic nanolasers using MOS structures. In particular, by using alloy-composition-varied indium gallium nitride/gallium nitride (InGaN/GaN) core-shell nanorods as the nanolaser gain media in the full visible spectrum, we are able to demonstrate full-color nanolasers that can be operated with ultralow CW lasing thresholds and single lasing modes. Full-color lasing in these subdiffraction plasmonic cavities is achieved via a unique autotuning mechanism based on a property of weak size dependence inherent in plasmonic nanolasers. As for choice of metals in the MOS structures, epitaxial Ag films and giant colloidal Ag crystals have been shown by us to be the superior constituent materials for plasmonic cavities due to their low plasmonic losses in the visible spectral range. Recently, we have also succeeded in developing InGaN/GaN nanorod array plasmonic lasers based on a metal (Au)-all-around MOS structure, which can be fabricated easily on a wafer scale. I will present the latest results in these developments.

  4. Picosecond Semiconductor Lasers For Characterizing High-Speed Image Shutters

    NASA Astrophysics Data System (ADS)

    Pagano, T. S.; Janson, F. J.; Yates, G. J.; Jaramillo, S. A.

    1986-01-01

    A portable system that utilizes solid state electronic timing circuits and a pulsed semiconductor laser for characterizing the optical gate sequence of high-speed image shutters, including microchannel-plate intensifier tubes (MCPTs), and silicon-intensified target vidicons (SITVs), is described and compared to earlier methods of characterization. Gate sequences obtained using the system and streak camera data of the semiconductor laser pulse are presented, with a brief discussion of the electronic delay timing and avalanche circuits used in the system.

  5. Continuously tunable wideband semiconductor fiber-ring laser

    NASA Astrophysics Data System (ADS)

    Mao, Xuefeng; Zhao, Shiwei; Yuan, Suzhen; Wang, Xiaofa; Zheng, Peichao

    2017-08-01

    We demonstrate a wideband tunable semiconductor fiber-ring laser that can be continuously tuned from 1498 nm to 1623 nm. The proposed laser uses a semiconductor optical amplifier (SOA) as a gain medium and a fiber Fabry-Perot tunable filter as a selective wavelength filter. The optimized drive current of the SOA and the output coupling ratio are obtained by experimental research. This laser has a simple configuration, low threshold, flat laser output power and high optical signal-to-noise ratio.

  6. EDITORIAL: Frontiers in semiconductor-based devices Frontiers in semiconductor-based devices

    NASA Astrophysics Data System (ADS)

    Krishna, Sanjay; Phillips, Jamie; Ghosh, Siddhartha; Ma, Jack; Sabarinanthan, Jayshri; Stiff-Roberts, Adrienne; Xu, Jian; Zhou, Weidong

    2009-12-01

    This special cluster of Journal of Physics D: Applied Physics reports proceedings from the Frontiers in Semiconductor-Based Devices Symposium, held in honor of the 60th birthday of Professor Pallab Bhattacharya by his former doctoral students. The symposium took place at the University of Michigan, Ann Arbor on 6-7 December 2009. Pallab Bhattacharya has served on the faculty of the Electrical Engineering and Computer Science Department at the University of Michigan, Ann Arbor for 25 years. During this time, he has made pioneering contributions to semiconductor epitaxy, characterization of strained heterostructures, self-organized quantum dots, quantum-dot optoelectronic devices, and integrated optoelectronics. Professor Bhattacharya has been recognized for his accomplishments by membership of the National Academy of Engineering, by chaired professorships (Charles M Vest Distinguished University Professor and James R Mellor Professor of Engineering), and by selection as a Fellow of the IEEE, among numerous other honors and awards. Professor Bhattacharya has also made remarkable contributions in education, including authorship of the textbook Semiconductor Optoelectronic Devices (Prentice Hall, 2nd edition) and the production of 60 PhD students (and counting). In fact, this development of critical human resources is one of the biggest impacts of Professor Bhattacharya's career. His guidance and dedication have shaped the varied professional paths of his students, many of whom currently enjoy successful careers in academia, industry, and government around the world. This special cluster acknowledges the importance of Professor Bhattacharya's influence as all of the contributions are from his former doctoral students. The symposium reflects the significant impact of Professor Bhattacharya's research in that the topics span diverse, critical research areas, including: semiconductor lasers and modulators, nanoscale quantum structure-based devices, flexible CMOS-based

  7. Monolayer semiconductor nanocavity lasers with ultralow thresholds

    DOE PAGES

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R.; ...

    2015-03-16

    Engineering the electromagnetic environment of a nanoscale light emitter by a photonic cavity can significantly enhance its spontaneous emission rate through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter1–5, providing the ultimate low-threshold laser system with small footprint, low power consumption and ultrafast modulation. A state-of-the-art ultra-low threshold nanolaser has been successfully developed though embedding quantum dots into photonic crystal cavity (PhCC)6–8. However, several core challenges impede the practical applications of this architecture, including the random positions and compositional fluctuations of the dots7, extreme difficulty in current injection8, and lackmore » of compatibility with electronic circuits7,8. Here, we report a new strategy to lase, where atomically thin crystalline semiconductor, i.e., a tungsten-diselenide (WSe2) monolayer, is nondestructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PhCC. A new type of continuous-wave nanolaser operating in the visible regime is achieved with an optical pumping threshold as low as 27 nW at 130 K, similar to the value achieved in quantum dot PhCC lasers7. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within 1 nm of the PhCC surface. The surface-gain geometry allows unprecedented accessibilities to multi-functionalize the gain, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.« less

  8. Monolayer semiconductor nanocavity lasers with ultralow thresholds

    SciTech Connect

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R.; Feng, Liefeng; Yan, Jiaqiang; Mandrus, David G.; Hatami, Fariba; Yao, Wang; Vučković, Jelena; Majumdar, Arka; Xu, Xiaodong

    2015-03-16

    Engineering the electromagnetic environment of a nanoscale light emitter by a photonic cavity can significantly enhance its spontaneous emission rate through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter1–5, providing the ultimate low-threshold laser system with small footprint, low power consumption and ultrafast modulation. A state-of-the-art ultra-low threshold nanolaser has been successfully developed though embedding quantum dots into photonic crystal cavity (PhCC)6–8. However, several core challenges impede the practical applications of this architecture, including the random positions and compositional fluctuations of the dots7, extreme difficulty in current injection8, and lack of compatibility with electronic circuits7,8. Here, we report a new strategy to lase, where atomically thin crystalline semiconductor, i.e., a tungsten-diselenide (WSe2) monolayer, is nondestructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PhCC. A new type of continuous-wave nanolaser operating in the visible regime is achieved with an optical pumping threshold as low as 27 nW at 130 K, similar to the value achieved in quantum dot PhCC lasers7. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within 1 nm of the PhCC surface. The surface-gain geometry allows unprecedented accessibilities to multi-functionalize the gain, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.

  9. High Power Mid Wave Infrared Semiconductor Lasers

    DTIC Science & Technology

    2006-06-15

    injected MWIR laser arrays using III-V antimonide based materials. In this approach, InGaSb quantum wells are grown on metamorphic layers on a GaSb or GaAs...also demonstrated room temperature photoluminescence up to 3 gm from InGaSb quantum wells grown on GaAs substrate. Using this approach we have...InAsSb/InAlAs quantum well lasers was reported with a To of 26K. Thus typically, the devices require thermoelectric or even cryogenic cooling to operate

  10. Hybrid organic semiconductor lasers for bio-molecular sensing.

    PubMed

    Haughey, Anne-Marie; Foucher, Caroline; Guilhabert, Benoit; Kanibolotsky, Alexander L; Skabara, Peter J; Burley, Glenn; Dawson, Martin D; Laurand, Nicolas

    2014-01-01

    Bio-functionalised luminescent organic semiconductors are attractive for biophotonics because they can act as efficient laser materials while simultaneously interacting with molecules. In this paper, we present and discuss a laser biosensor platform that utilises a gain layer made of such an organic semiconductor material. The simple structure of the sensor and its operation principle are described. Nanolayer detection is shown experimentally and analysed theoretically in order to assess the potential and the limits of the biosensor. The advantage conferred by the organic semiconductor is explained, and comparisons to laser sensors using alternative dye-doped materials are made. Specific biomolecular sensing is demonstrated, and routes to functionalisation with nucleic acid probes, and future developments opened up by this achievement, are highlighted. Finally, attractive formats for sensing applications are mentioned, as well as colloidal quantum dots, which in the future could be used in conjunction with organic semiconductors.

  11. Industrial integration of high coherence tunable single frequency semiconductor lasers based on VECSEL technology for scientific instrumentation in NIR and MIR

    NASA Astrophysics Data System (ADS)

    Lecocq, Vincent; Chomet, Baptiste; Ferrières, Laurence; Myara, Mikhaël.; Beaudoin, Grégoire; Sagnes, Isabelle; Cerutti, Laurent; Denet, Stéphane; Garnache, Arnaud

    2017-02-01

    Laser technology is finding applications in areas such as high resolution spectroscopy, radar-lidar, velocimetry, or atomic clock where highly coherent tunable high power light sources are required. The Vertical External Cavity Surface Emitting Laser (VECSEL) technology [1] has been identified for years as a good candidate to reach high power, high coherence and broad tunability while covering a wide emission wavelength range exploiting III-V semiconductor technologies. Offering such performances in the Near- and Middle-IR range, GaAs- and Sb-based VECSEL technologies seem to be a well suited path to meet the required specifications of demanding applications. Built up in this field, our expertise allows the realization of compact and low power consumption marketable products, with performances that do not exist on the market today in the 0.8-1.1 μm and 2-2.5 μm spectral range. Here we demonstrate highly coherent broadly tunable single frequency laser micro-chip, intracavity element free, based on a patented VECSEL technology, integrated into a compact module with driving electronics. VECSEL devices emitting in the Near and Middle-IR developed in the frame of this work [2] exhibit exciting features compared to diode-pumped solid-state lasers and DFB diode lasers; they combine high power (>100mW) high temporal coherence together with a low divergence diffraction limited TEM00 beam. They exhibit a class-A dynamics with a Relative Intensity Noise as low as -140dB/Hz and at shot noise level reached above 200MHz RF frequency (up to 160GHz), a free running narrow linewidth at sub MHz level (fundamental limit at Hz level) with high spectral purity (SMSR >55dB), a linear polarization (>50dB suppression ratio), and broadband continuous tunability greater than 400GHz (< 30V piezo voltage, 6kHz cut off frequency) with total tunability up to 3THz. Those performances can all be reached thanks to the high finesse cavity of VECSEL technology, associated to ideal homogeneous QW

  12. High-power semiconductor laser array packaged on microchannel cooler using gold-tin soldering technology

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Kang, Lijun; Zhang, Pu; Nie, Zhiqiang; Li, Xiaoning; Xiong, Lingling; Liu, Xingsheng

    2012-03-01

    High power semiconductor laser arrays have found increased applications in many fields. In this work, a hard soldering microchannel cooler (HSMCC) technology was developed for packaging high power diode laser array. Numerical simulations of the thermal behavior characteristics of hard solder and indium solder MCC-packaged diode lasers were conducted and analyzed. Based on the simulated results, a series of high power HSMCC packaged diode laser arrays were fabricated and characterized. The test and statistical results indicated that under the same output power the HSMCC packaged laser bar has lower smile and high reliability in comparison with the conventional copper MCC packaged laser bar using indium soldering technology.

  13. Influence of the electrical contact on the reliability of InP-based ridge waveguide distributed feedback semiconductor diode lasers for telecommunications applications

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Boudreau, M. G.; Kuchibhatla, R.; Tao, Y.; Das, S. R.; Griswold, E. M.; Sharma, U.

    2004-05-01

    The design of a ridge waveguide semiconductor diode laser requires the definition of a high-quality metal contact to a p-type semiconductor that has been patterned to form the laser ridge. In the InGaAsP material system, Zn-doped, p-InGaAs is used as the contact layer. An evaporated multilayer metal stack consisting of Ti, Pt, and Au is alloyed to the InGaAs to form a stable ohmic contact with good adhesion. The alloying process is an intermixing of the Ti and As. Pt is not reactive during the alloying process and acts as a diffusion barrier. In this work, the Pt and Ti layer thicknesses were varied to improve the laser reliability. The layer thicknesses were optimized with the goal of producing a minimum stress in the laser active region. A preliminary study of completely processed lasers indicates that the laser reliability is significantly influenced by the changes to the stress induced in the device by the p-contact metal stack. Further work is required to establish the relationship between the stress in the active region of the device, and the stress contribution from the p-contact metal stack. .

  14. Reduced Auger Recombination in Mid-Infrared Semiconductor Lasers (POSTPRINT)

    DTIC Science & Technology

    2013-02-01

    overcome for successful system adoption. Within the last 15 years, quantum cascade lasers ( QCLs ) have proven to be a very capable semiconductor laser...restricted at the longer wavelengths, compared to QCLs due to band filling.9 In the short-wave and mid-wave infrared wavelengths, their low T0

  15. Phase control and beam steering of semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1982-01-01

    The operational principles and a possible device configuration of one dimensional monolithically integrated semiconductor laser arrays are described. The output beam of the array can be electronically steered. Devices of the type can find applications in optical communication systems where the power levels needed are above the capability of a single laser device.

  16. Broadly tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Hackett, Shawn; Sheik-Bahae, Mansoor

    2016-03-01

    We report a DBR-free semiconductor disk lasers centered at 1160 nm with a tuning range of 78 nm, and ongoing effort on our DBR-free SDL centered at 1040 nm. Compared with conventional semiconductor disk lasers, DBR-free SDLs have a broader effective gain bandwidth. In CW operation, 2.5 W output power at 1160 nm and 6 W at 1055 nm were collected from the two lasers without thermal-rollover. Intracavity loss mitigation, currently underway, should improve power scaling and efficiency in these systems.

  17. FM characteristics and compact modules for coherent semiconductor lasers coupled to an external cavity

    SciTech Connect

    Shin, C.H.; Teshima, M.; Ohtsu, M. ); Imai, T.; Yoshida, J.; Nishide, K. )

    1990-03-01

    FM responses of a semiconductor laser optically coupled off-axis to a confocal Fabry--Perot cavity were measured. It is reported that this cavity acted as a frequency discriminator and as a phase comparator for slow and fast frequency fluctuations, respectively. The crossover between them was determined by a half linewidth of the cavity. Based on these investigations, we made two kinds of coherent semiconductor laser modules. External FP cavities were made by using an optical fiber and a hemispherical micro-lens, respectively. Linewidths of these lasers were less than 25 kHz.

  18. Thienoacene-based organic semiconductors.

    PubMed

    Takimiya, Kazuo; Shinamura, Shoji; Osaka, Itaru; Miyazaki, Eigo

    2011-10-11

    Thienoacenes consist of fused thiophene rings in a ladder-type molecular structure and have been intensively studied as potential organic semiconductors for organic field-effect transistors (OFETs) in the last decade. They are reviewed here. Despite their simple and similar molecular structures, the hitherto reported properties of thienoacene-based OFETs are rather diverse. This Review focuses on four classes of thienoacenes, which are classified in terms of their chemical structures, and elucidates the molecular electronic structure of each class. The packing structures of thienoacenes and the thus-estimated solid-state electronic structures are correlated to their carrier transport properties in OFET devices. With this perspective of the molecular structures of thienoacenes and their carrier transport properties in OFET devices, the structure-property relationships in thienoacene-based organic semiconductors are discussed. The discussion provides insight into new molecular design strategies for the development of superior organic semiconductors. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Semiconductor Laser Multi-Spectral Sensing and Imaging

    PubMed Central

    Le, Han Q.; Wang, Yang

    2010-01-01

    Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers. PMID:22315555

  20. Direct solar pumping of semiconductor lasers: A feasibility study

    NASA Technical Reports Server (NTRS)

    Anderson, Neal G.

    1992-01-01

    This report describes results of NASA Grant NAG-1-1148, entitled Direct Solar Pumping of Semiconductor Lasers: A Feasibility Study. The goals of this study were to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space with directly focused sunlight and to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or storage battery electrically pumping a current injection laser. With external modulation, such lasers could perhaps be efficient sources for intersatellite communications. We proposed specifically to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation at low pump intensities. These tasks have been accomplished, as described in this report of our completed project. The report is organized as follows: Some general considerations relevant to the solar-pumped semiconductor laser problem are discussed in Section 2, and the types of structures chosen for specific investigation are described. The details of the laser model we developed for this work are then outlined in Section 3. In Section 4, results of our study are presented, including designs for optimum lattice-matched and strained-layer solar-pumped quantum-well lasers and threshold pumping estimates for these structures. It was hoped at the outset of this work that structures could be identified which could be expected to operate continuously at solar photoexcitation intensities of several thousand suns, and this indeed turned out to be the case as described in this section. Our project is

  1. Semiconductor laser multi-spectral sensing and imaging.

    PubMed

    Le, Han Q; Wang, Yang

    2010-01-01

    Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

  2. The 1.083 micron tunable CW semiconductor laser

    NASA Technical Reports Server (NTRS)

    Wang, C. S.; Chen, Jan-Shin; Lu, Ken-Gen; Ouyang, Keng

    1991-01-01

    A tunable CW laser is desired to produce light equivalent to the helium spectral line at 1.08 microns. This laser will serve as an optical pumping source for He-3 and He-4 atoms used in space magnetometers. This light source can be fabricated either as a semiconductor laser diode or a pumped solid state laser. Continuous output power of greater than 10 mW is desired. Semiconductor lasers can be thermally tuned, but must be capable of locking onto the helium resonance lines. Solid state lasers must have efficient pumping sources suitable for space configuration. Additional requirements are as follows: space magnetometer applications will include low mass (less than 0.5 kg), low power consumption (less than 0.75 W), and high stability/reliability for long missions (5-10 years).

  3. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    SciTech Connect

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V; Ladugin, M A; Marmalyuk, A A; Chamorovsky, A Yu; Yakubovich, S D

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  4. Monolithically integrated semiconductor ring lasers: Design, fabrication, and directional control

    NASA Astrophysics Data System (ADS)

    Cao, Hongjun

    Monolithic semiconductor ring lasers (SRLs) are attractive light sources for optoelectronic integrated circuits (OEICs) due to their convenience in monolithic integration: neither cleaved facets nor gratings are required for optical feedback. They are promising candidates for wavelength filtering, multiplexing-demultiplexing applications, electrical or all-optical switching, gating, and memories, and particularly, optical inertial rotation sensors or ring laser gyros. As the major part of a NASA-supported project "Monolithically integrated semiconductor ring laser gyro for space applications," this dissertation research was focused on design, fabrication, and directional control of monolithically integrated SRLs with relatively large size and sophisticated OEIC structures. The main potential application is the next-generation monolithic ring laser gyros. Specifically, monolithic SRLs with the longest reported cavity of 10.28 mm have been demonstrated. In device characterization, differential I-V analysis has been used for the first time in SRLs for purely electrical identification of lasing threshold and directional switching. Sophisticated device structures have been devised, including optically independent novel ring laser pairs, from which frequency beating between monolithically integrated SRLs was reported for the first time. In addition, no frequency lock-in was observed in the beating spectra, indicating an important progress for proposed gyro applications. Functional OEIC components including photodetectors, passive and active waveguides, and novel Joule heaters have been integrated on-chip along with the ring lasers. Mode competition, directional switching, bistability, and bidirectional and unidirectional operation in SRLs have been investigated. Directional control techniques with asymmetric mechanisms including spiral and S-section waveguides have been implemented. The S-section was investigated and analyzed in great detail for its suppression of

  5. Metal Organic-Chemical Vapor Deposition fabrication of semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Thomas, C.

    1980-08-01

    The metal organic chemical vapor deposition (MO-CVD) process was studied and implemented in detail. Single crystal GaAs, and Ga(x)Al(1-x)As films were grown on GaAs by depositing metal organic alkyl gallium compounds in the presence of an arsine mixture. The metal organic chemical vapor deposition process allowed formation of the semiconductor compound directly on the heated substrate in only one hot temperature zone. With MO-CVD, semiconductor films can be efficiently produced by a more economical, less complicated process which will lend itself more easily than past fabrication procedures, to high quantity, high quality reproduction techniques of semiconductor lasers. Clearly MO-CVD is of interest to the communication industry where semiconductor lasers are used extensively in fiber optic communication systems, and similarly to the solar energy business where GaAs substrates are used as photoelectric cells.

  6. Six-wave mixing theory of tilted-grating, broad-area semiconductor diode lasers with suppressed filamentation

    NASA Astrophysics Data System (ADS)

    Thompson, William Ellison, III

    Modern semiconductor diode lasers are appealing sources of laser radiation for many applications. However, an important disadvantage of semiconductor diode lasers as laser sources for the widest range of applications is that they are limited in output power. The output power of typical narrow-stripe semiconductor diode lasers is limited by thermal runaway effects that cause catastrophic facet damage to the device. To address this problem, researchers have developed broad-area diode lasers that can achieve increased output power by virtue of their larger emission area on the facet. In practice, however, the loss of lateral confinement that produces single-mode lasing in narrow-stripe semiconductor diode lasers leads to complex, multi-mode lasing in broad-area semiconductor diode lasers. The lateral spatial distribution of laser energy is further complicated by an optical nonlinearity in the semiconductor laser gain region, due to the dependence of the refractive index on the free-charge carrier density. This nonlinearity is responsible for the self-deformation of the lateral field distribution, so that in the lateral direction, the active region has areas of higher and lower light intensity, often called filaments. This highly-nonuniform lateral field distribution results in poor beam quality and hot-spot facet damage at relatively low output power for typical broad-area semiconductor diode lasers. This dissertation proposes and analyzes a specific approach to suppress filamentation in broad-area semiconductor diode lasers, with the general goal of increasing the laser power that can be produced while retaining good beam quality. The analysis approach is based on a six-wave mixing methodology for the evaluation of filamentation in general broad-area semiconductor diode laser structures. This methodology is first applied to examine the growth of filamentation in typical broad-area semiconductor diode laser designs. A specific design modification to a broad-area laser

  7. Plastic lab-on-a-chip for fluorescence excitation with integrated organic semiconductor lasers.

    PubMed

    Vannahme, Christoph; Klinkhammer, Sönke; Lemmer, Uli; Mappes, Timo

    2011-04-25

    Laser light excitation of fluorescent markers offers highly sensitive and specific analysis for bio-medical or chemical analysis. To profit from these advantages for applications in the field or at the point-of-care, a plastic lab-on-a-chip with integrated organic semiconductor lasers is presented here. First order distributed feedback lasers based on the organic semiconductor tris(8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyril)-4H-pyrane (DCM), deep ultraviolet induced waveguides, and a nanostructured microfluidic channel are integrated into a poly(methyl methacrylate) (PMMA) substrate. A simple and parallel fabrication process is used comprising thermal imprint, DUV exposure, evaporation of the laser material, and sealing by thermal bonding. The excitation of two fluorescent marker model systems including labeled antibodies with light emitted by integrated lasers is demonstrated.

  8. Laser-based irradiation apparatus and methods for monitoring the dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2006-03-28

    A scanned, pulsed, focused laser irradiation apparatus can measure and image the photocurrent collection resulting from a dose-rate equivalent exposure to infrared laser light across an entire silicon die. Comparisons of dose-rate response images or time-delay images from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems allows precise identification of those specific age-affected circuit structures within a device that merit further quantitative analysis with targeted materials or electrical testing techniques. Another embodiment of the invention comprises a broad-beam, dose rate-equivalent exposure apparatus. The broad-beam laser irradiation apparatus can determine if aging has affected the device's overall functionality. This embodiment can be combined with the synchronized introduction of external electrical transients into a device under test to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure.

  9. Semiconductor Laser Diodes and the Design of a D.C. Powered Laser Diode Drive Unit

    DTIC Science & Technology

    1988-06-01

    i FILE c(OP!; NAVAL POSTGRADUATE SCHOOL Monterey, California 00 ,, STAES THESIS SEMICONDUCTOR LASER DIODES AND THE DESIGN OF A D.C. POWERED LASER...the design of a laser diode modulation circuit is the determination of the input imped- ence and equivalent circuit of the laser diode and packag- ing...current source with a high internal impedance as compared to the input imped- ance of the laser. [Ref. l:p. 33] Summarizing the above, laser diodes

  10. Femtosecond laser deposition of semiconductor quantum dot films

    NASA Astrophysics Data System (ADS)

    Oraiqat, Ibrahim; Kennedy, Jack; Mathis, James; Clarke, Roy

    2012-07-01

    We report new results on the deposition of high-density films of semiconductor nanostructures by ultrafast pulsed laser deposition (UFPLD). Such materials are of interest for advanced optoelectronic applications such as quantum dot lasers and energy harvesting devices. The deposition method utilizes the interaction of a focused chirped pulse amplified (CPA) Ti-sapphire laser beam with a solid target (a rotating semiconductor wafer) to produce a hot-dense plasma at the target surface with a power density in excess of 1014 W/cm2. The plasma then undergoes rapid expansion and the resulting condensation process produces a high density of nanoscale particles (average size of a few nm) on a substrate placed a few cm from the target. We have investigated several semiconductor quantum dot systems including silicon and germanium. We observed a significant blue-shift of the optical absorption edge indicating quantum confinement effects which may be of interest for photovoltaic applications.

  11. Heteroclinic dynamics of coupled semiconductor lasers with optoelectronic feedback.

    PubMed

    Shahin, S; Vallini, F; Monifi, F; Rabinovich, M; Fainman, Y

    2016-11-15

    Generalized Lotka-Volterra (GLV) equations are important equations used in various areas of science to describe competitive dynamics among a population of N interacting nodes in a network topology. In this Letter, we introduce a photonic network consisting of three optoelectronically cross-coupled semiconductor lasers to realize a GLV model. In such a network, the interaction of intensity and carrier inversion rates, as well as phases of laser oscillator nodes, result in various dynamics. We study the influence of asymmetric coupling strength and frequency detuning between semiconductor lasers and show that inhibitory asymmetric coupling is required to achieve consecutive amplitude oscillations of the laser nodes. These studies were motivated primarily by the dynamical models used to model brain cognitive activities and their correspondence with dynamics obtained among coupled laser oscillators.

  12. Optical efficiency and gain dynamics of modelocked semiconductor disk lasers.

    PubMed

    Alfieri, C G E; Waldburger, D; Link, S M; Gini, E; Golling, M; Eisenstein, G; Keller, U

    2017-03-20

    Compact optically pumped passively modelocked semiconductor disk lasers (SDLs) based on active quantum wells (QWs) such as vertical external-cavity surface-emitting lasers (VECSELs) or modelocked integrated external-cavity surface-emitting lasers (MIXSELs) are wavelength-versatile sources that offer a unique combination of gigahertz pulse repetition rates and short pulse durations. In this paper, we present record-short pulses of 184 fs from a gigahertz MIXSEL emitting at a center wavelength of 1048 nm. This result comes at the expense of low optical-to-optical pump efficiency (<1%) and average output power limited to 115 mW. We experimentally observe that shorter pulses significantly reduce the macroscopic gain saturation fluence and develop a QW model based on rate equations to reproduce the gain saturation behavior and quantitatively explain the VECSEL and MIXSEL modelocking performances. We identify spectral hole burning as the main cause of the reduced gain at shorter pulse durations, which in combination with the short lifetime of the excited carriers strongly reduces the optical pump efficiency. Our better understanding will help to address these limitations in future ultrafast SDL designs.

  13. Laser interferometric method for determining the carrier diffusion length in semiconductors

    SciTech Connect

    Manukhov, V. V.; Fedortsov, A. B.; Ivanov, A. S.

    2015-09-15

    A new laser interferometric method for measuring the carrier diffusion length in semiconductors is proposed. The method is based on the interference–absorption interaction of two laser radiations in a semiconductor. Injected radiation generates additional carriers in a semiconductor, which causes a change in the material’s optical constants and modulation of the probing radiation passed through the sample. When changing the distance between carrier generation and probing points, a decrease in the carrier concentration, which depends on the diffusion length, is recorded. The diffusion length is determined by comparing the experimental and theoretical dependences of the probe signal on the divergence of the injector and probe beams. The method is successfully tested on semiconductor samples with different thicknesses and surface states and can be used in scientific research and the electronics industry.

  14. Reliability of Semiconductor Laser Packaging in Space Applications

    NASA Technical Reports Server (NTRS)

    Gontijo, Ivair; Qiu, Yueming; Shapiro, Andrew A.

    2008-01-01

    A typical set up used to perform lifetime tests of packaged, fiber pigtailed semiconductor lasers is described, as well as tests performed on a set of four pump lasers. It was found that two lasers failed after 3200, and 6100 hours under device specified bias conditions at elevated temperatures. Failure analysis of the lasers indicates imperfections and carbon contamination of the laser metallization, possibly from improperly cleaned photo resist. SEM imaging of the front facet of one of the lasers, although of poor quality due to the optical fiber charging effects, shows evidence of catastrophic damage at the facet. More stringent manufacturing controls with 100% visual inspection of laser chips are needed to prevent imperfect lasers from proceeding to packaging and ending up in space applications, where failure can result in the loss of a space flight mission.

  15. Reliability of Semiconductor Laser Packaging in Space Applications

    NASA Technical Reports Server (NTRS)

    Gontijo, Ivair; Qiu, Yueming; Shapiro, Andrew A.

    2008-01-01

    A typical set up used to perform lifetime tests of packaged, fiber pigtailed semiconductor lasers is described, as well as tests performed on a set of four pump lasers. It was found that two lasers failed after 3200, and 6100 hours under device specified bias conditions at elevated temperatures. Failure analysis of the lasers indicates imperfections and carbon contamination of the laser metallization, possibly from improperly cleaned photo resist. SEM imaging of the front facet of one of the lasers, although of poor quality due to the optical fiber charging effects, shows evidence of catastrophic damage at the facet. More stringent manufacturing controls with 100% visual inspection of laser chips are needed to prevent imperfect lasers from proceeding to packaging and ending up in space applications, where failure can result in the loss of a space flight mission.

  16. 80 nm tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Albrecht, A. R.; Cederberg, J. G.; Sheik-Bahae, M.

    2016-07-01

    We report a widely tunable optically pumped distributed Bragg reflector (DBR)-free semiconductor disk laser with 6 W continuous wave output power near 1055 nm when using a 2% output coupler. Using only high reflecting mirrors, the lasing wavelength is centered at 1034 nm and can be tuned up to a record 80 nm by using a birefringent filter. We attribute such wide tunability to the unique broad effective gain bandwidth of DBR-free semiconductor disk lasers achieved by eliminating the active mirror geometry.

  17. Pulse operation of semiconductor laser with nonlinear optical feedback

    NASA Astrophysics Data System (ADS)

    Guignard, Celine; Besnard, Pascal; Mihaescu, Adrian; MacDonald, K. F.; Pochon, Sebastien; Zheludev, Nikolay I.

    2004-09-01

    A semiconductor laser coupled to a gallium-made non linear mirror may exhibit pulse regime. In order to better understand this coupled cavity, stationary solutions and dynamics are described following the standard Lang and Kobayashi equations for a semiconductor laser submitted to nonlinear optical feedback. It is shown that the nonlinearity distorts the ellipse on which lied the stationary solutions, with a ``higher'' part corresponding to lower reflectivity and a ``lower'' part to higher reflectivity. Bifurcation diagrams and nonlinear analysis are presented while the conditions for pulsed operation are discussed.

  18. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G.R.; Hohimer, J.P.; Owyoung, A.

    1991-02-19

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet. 18 figures.

  19. Integrated injection-locked semiconductor diode laser

    DOEpatents

    Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1991-01-01

    A continuous wave integrated injection-locked high-power diode laser array is provided with an on-chip independently-controlled master laser. The integrated injection locked high-power diode laser array is capable of continuous wave lasing in a single near-diffraction limited output beam at single-facet power levels up to 125 mW (250 mW total). Electronic steering of the array emission over an angle of 0.5 degrees is obtained by varying current to the master laser. The master laser injects a laser beam into the slave array by reflection of a rear facet.

  20. A 3000W 808nm QCW G-stack semiconductor laser array

    NASA Astrophysics Data System (ADS)

    Zhang, Pu; Wang, Jingwei; Hou, Dong; Wang, Zhenfu; Xiong, Lingling; Liu, Hui; Nie, Zhiqiang; Liu, Xingsheng

    2015-02-01

    With the improvement of output power, efficiency and reliability, high power semiconductor lasers have been applied in more and more fields. In this paper, a conduction-cooled, high peak output power semiconductor laser array was studied and developed. The structure and operation parameters of G-Stack semiconductor laser array were designed and optimized using finite element method (FEM). A Quasi-continuous-wave (QCW) conduction-cooled G-Stack semiconductor laser array with a narrow spectrum width was fabricated successfully.

  1. Deep-red semiconductor monolithic mode-locked lasers

    SciTech Connect

    Kong, L.; Bajek, D.; White, S. E.; Forrest, A. F.; Cataluna, M. A.; Wang, H. L.; Pan, J. Q.; Wang, X. L.; Cui, B. F.; Ding, Y.

    2014-12-01

    A deep-red semiconductor monolithic mode-locked laser is demonstrated. Multi-section laser diodes based on an AlGaAs multi-quantum-well structure were passively mode-locked, enabling the generation of picosecond optical pulses at 752 nm, at pulse repetition rates of 19.37 GHz. An investigation of the dependence of the pulse duration as a function of reverse bias revealed a predominantly exponential decay trend of the pulse duration, varying from 10.5 ps down to 3.5 ps, which can be associated with the concomitant reduction of absorption recovery time with increasing applied field. A 30-MHz-tunability of the pulse repetition rate with bias conditions is also reported. The demonstration of such a compact, efficient and versatile ultrafast laser in this spectral region paves the way for its deployment in a wide range of applications such as biomedical microscopy, pulsed terahertz generation as well as microwave and millimeter-wave generation, with further impact on sensing, imaging and optical communications.

  2. Existence of continuous-wave threshold for organic semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Zhang, Yifan; Forrest, Stephen R.

    2011-12-01

    We develop a model that predicts two threshold pump intensities in optically pumped organic semiconductor lasers (OSLs); one for pulsed lasing, IPS, and another for continuous-wave (CW) lasing, ICW. The theory predicts a decrease in ICW from 32 kW/cm2, or well above the damage threshold, to 2.2 kW/cm2, for a laser employing 4-(dicyanomethylene)-2-methyl-6-julolidyl-9-enyl-4H-pyran-doped tris(8-hydroxyquinoline) aluminum if the triplets can be effectively removed from the emissive guest. Based on this analysis, we demonstrate that the lasing duration can be extended to nearly 100 μs, ultimately limited by degradation of the lasing medium when a “triplet manager” molecule, 9,10-di(naphtha-2-yl)anthracene, is blended into the gain region of an otherwise conventional distributed feedback OSL. The triplet manager facilitates radiative singlet transfer while suppressing nonradiative triplet transfer to the emitter molecule, thus reducing the triplet-induced losses. Our theory conclusively shows that these lasers have entered the CW lasing regime.

  3. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    SciTech Connect

    Chamorovskiy, A Yu; Okhotnikov, Oleg G

    2012-11-30

    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  4. Phase stability of injection-locked beam of semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Kwon, Jin Hyuk; Kim, Do Hoon; Schuster, Gregory; Lee, Ja H.

    1992-01-01

    An experiment on the phase stability of an injection locked beam was done by using AlGaAs semiconductor lasers. The coherence of two beams from master and slave lasers was measured by interference between the beams in the Twymann-Green interferometer. The phase change of the output beam of the slave laser as a function of the driving current was measured in a Mach-Zehnder interferometer consisting of the master and slave lasers, and a value of 2.5 radians/mA was obtained.

  5. Dynamics of Semiconductor Microcavities Using Ultrashort Pulse Lasers

    NASA Astrophysics Data System (ADS)

    Rhee, June-Koo

    1995-01-01

    Using femtosecond optical spectroscopy, we perform an extensive study of dynamics of an AlAs/AlGaAs/GaAs-based semiconductor quantum microcavity, which exhibit cavity -polariton behavior owing to strong coupling between the exciton and cavity modes. We explore the dynamics of time -domain vacuum Rabi oscillations, the spatial coherence transfer of cavity-polariton states, and cavity-polariton dynamics in the nonlinear regime. In the time domain, when the microcavity is impulsively excited by a short coherent optical pulse, we observe the vacuum Rabi oscillations in the radiation, corresponding to the cavity-polariton mode splitting of the microcavity. Interferometric pump-probe measurements clearly show the coherent evolution of the cavity-polaritons. At high intensity, the normal mode splitting collapses due to bleaching of the excitonic oscillator strength. The dynamics of the splitting reveal the momentum relaxation of the cavity-polaritons due to inhomogeneous broadening, and provides evidence for delayed exciton-exciton scattering due to vacuum Rabi oscillation. When the cavity is excited coherently at an oblique angle, we also observe coherent radiation in the normal direction of the substrate, with a nearly fixed delay of 450 fs. This radiation is coherent with the excitation pulse and dependent on excitation density. Specifically, the initially-excited spatial cavity-polariton state is coherently transferred to the other spatial state selected by the cavity mode. The excitation dependence suggests this coherence transfer is associated with exciton scatterings. A density-matrix analysis for two cavity-polariton systems shows our model is in good qualitative agreement with the experiment. In order to perform femtosecond semiconductor spectroscopic experiments, it was necessary to develop the ultrafast laser source. We describe a cw-argon-laser -pumped Ti:sapphire laser system and a real-time femtosecond -optical-pulse analyzer, for femtosecond spectroscopy

  6. Researching the 915 nm high-power and high-brightness semiconductor laser single chip coupling module

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Wang, Cuiluan; Wu, Xia; Zhu, Lingni; Jing, Hongqi; Ma, Xiaoyu; Liu, Suping

    2017-02-01

    Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2 -str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.

  7. Zinc oxide based diluted magnetic semiconductor nanoparticles: Synthesis by laser ablation in liquids, microstructural and optical properties

    SciTech Connect

    Savchuk, Andriy I.; Stolyarchuk, Ihor D.; Savchuk, Oleksandr A.; Makoviy, Vitaliy V.; Smolinsky, Mykhailo M.; Shporta, Oleksandra A.; Perrone, Alessio

    2013-12-04

    Nanoparticles of ZnO and ZnO doped with transition metals (Mn, Co) were synthesized by laser ablation in liquid medium. Scanning electron microscopy (SEM) showed formation of nanostructures with different shapes. Atomic force microscopy (AFM) gives information about surface morphology of the formed nanostructures. Absorption edge of ZnO, ZnO:Mn and ZnO:Co colloidal nanoparticles exhibits blue shift due to confinement effect. In photoluminescence spectra three peaks are attributed to the band-edge transitions and defect states. The Faraday rotation in ZnO:Mn nanoparticles gives evidence for paramagnetic behavior at room temperature.

  8. All semiconductor laser Doppler anemometer at 1.55 microm.

    PubMed

    Hansen, René Skov; Pedersen, Christian

    2008-10-27

    We report to our best knowledge the first all semiconductor Laser Doppler Anemometer (LIDAR) for wind speed determination. We will present the design and first experimental results on a focusing coherent cw laser Doppler anemometer for measuring atmospheric wind velocities in the 10 meters to 300 meters distance range. Especially, we will demonstrate that both the output power as well as the demanding coherence properties required from the laser source can be accomplished by an all semiconductor laser. Preliminary tests at a distance of 40 meters indicate a typical signal to noise ratio of 9 dB. This result is obtained at a clear day with an up-date rate of 12 Hz.

  9. Recent progress in picosecond pulse generation from semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    This paper reviews the recent progress in producing picosecond optical pulses from semiconductor laser diodes. The discussion concentrates on the mode-locking of a semiconductor laser diode in an external resonator. Transform-limited optical pulses ranging from several picoseconds to subpicosecond durations have been observed with active and passive mode-locking. Even though continuing research on the influence of impurities and defects on the mode-locking process is still needed, this technique has good promise for being utilized in fiber-optic communication systems. Alternative methods of direct electrical and optical excitation to produce ultrashort laser pulses are also described. They can generate pulses of similar widths to those obtained by mode-locking. The pulses generated will find applications in laser ranging and detector response measurement.

  10. Recent progress in picosecond pulse generation from semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    This paper reviews the recent progress in producing picosecond optical pulses from semiconductor laser diodes. The discussion concentrates on the mode-locking of a semiconductor laser diode in an external resonator. Transform-limited optical pulses ranging from several picoseconds to subpicosecond durations have been observed with active and passive mode-locking. Even though continuing research on the influence of impurities and defects on the mode-locking process is still needed, this technique has good promise for being utilized in fiber-optic communication systems. Alternative methods of direct electrical and optical excitation to produce ultrashort laser pulses are also described. They can generate pulses of similar widths to those obtained by mode-locking. The pulses generated will find applications in laser ranging and detector response measurement.

  11. Fast random number generation with spontaneous emission noise of a single-mode semiconductor laser

    NASA Astrophysics Data System (ADS)

    Zhang, Jianzhong; Zhang, Mingjiang; Liu, Yi; Li, Pu; Yi, Xiaogang; Zhang, Mingtao; Wang, Yuncai

    2016-11-01

    We experimentally demonstrate a 12.5 Gb s-1 random number generator based on measuring the spontaneous emission noise of a single-mode semiconductor laser. The spontaneous emission of light is quantum mechanical in nature and is an inborn physical entropy source of true randomness. By combining a high-speed analog-to-digital converter and off-line processing, random numbers are extracted from the spontaneous emission with the verified randomness. The generator is simple, robust, and with no need of accurately tuning the comparison threshold. The use of semiconductor lasers makes it particularly compatible with the delivery of random numbers in optical networks.

  12. Semiconductor lasers vs LEDs in diagnostic and therapeutic medicine

    NASA Astrophysics Data System (ADS)

    Gryko, Lukasz; Zajac, Andrzej; Szymanska, Justyna; Blaszczak, Urszula; Palkowska, Anna; Kulesza, Ewa

    2016-12-01

    Semiconductor emitters are used in many areas of medicine, allowing for new methods of diagnosis, treatment and effective prevention of many diseases. The article presents selected areas of application of semiconductor sources in UVVIS- NIR range, where in recent years competition in semiconductor lasers and LEDs applications has been observed. Examples of applications of analyzed sources are indicated for LLLT, PDT and optical diagnostics using the procedure of color contrast. Selected results of LLLT research of the authors are presented that were obtained by means of the developed optoelectronic system for objectified irradiation and studies on the impact of low-energy laser and LED on lines of endothelial cells of umbilical vein. Usefulness of the spectrally tunable LED lighting system for diagnostic purposes is also demonstrated, also as an illuminator for surface applications - in procedure of variable color contrast of the illuminated object.

  13. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Refractive indices of superlattices made of III-V semiconductor compounds and their solid solutions and semiconductor waveguide laser structures

    NASA Astrophysics Data System (ADS)

    Unger, K.

    1988-11-01

    An analysis is made of the theoretical problems encountered in precision calculations of refractive indices of semiconductor materials arising in connection with the use of superlattices as active layers in double-heterostructure lasers and in connection with the use of the impurity-induced disordering effect, i.e., the ability to transform selectively a superlattice into a corresponding solid solution. This can be done by diffusion or ion implantation. A review is given of calculations of refractive indices based on the knowledge of the energy band structure and the role of disorder is considered particularly. An anomaly observed in the (InAl)As system is considered. It is shown that the local field effects and exciton transitions are important. A reasonable approach is clearly a direct calculation of the difference between the refractive indices of superlattices based on compounds and of those based on their solid solutions.

  14. Photoelectrolysis of water at high current density - Use of laser light excitation of semiconductor-based photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Bocarsley, A. B.; Bolts, J. M.

    1978-01-01

    In the present paper, some results are given for UV laser light irradiation of the photoanode (SnO2, SrTiO3, or TiO2) in a cell for the light-driven electrolysis of H2O, at radiation intensities of up to 380 W/sq cm. The properties of the anode material are found to be independent of light intensity. Conversion of UV light to stored chemical energy in the form of 2H2/O2 from H2O was driven at a rate of up to 30 W/sq cm. High O2 evolution rates at the irradiated anodes without changes in the current-voltage curves are attributed to the excess oxidizing power associated with photogenerated holes. A test for this sort of hypothesis for H2 evolution at p-type materials is proposed.

  15. Photoelectrolysis of water at high current density - Use of laser light excitation of semiconductor-based photoelectrochemical cells

    NASA Technical Reports Server (NTRS)

    Wrighton, M. S.; Bocarsley, A. B.; Bolts, J. M.

    1978-01-01

    In the present paper, some results are given for UV laser light irradiation of the photoanode (SnO2, SrTiO3, or TiO2) in a cell for the light-driven electrolysis of H2O, at radiation intensities of up to 380 W/sq cm. The properties of the anode material are found to be independent of light intensity. Conversion of UV light to stored chemical energy in the form of 2H2/O2 from H2O was driven at a rate of up to 30 W/sq cm. High O2 evolution rates at the irradiated anodes without changes in the current-voltage curves are attributed to the excess oxidizing power associated with photogenerated holes. A test for this sort of hypothesis for H2 evolution at p-type materials is proposed.

  16. Direct solar pumping of semiconductor lasers: A feasibility study

    NASA Technical Reports Server (NTRS)

    Anderson, Neal G.

    1991-01-01

    The primary goals of the feasibility study are the following: (1) to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space directly focused sunlight; and (2) to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or battery electrically pumping a current injection laser. With external modulation, such lasers may prove to be efficient sources for intersatellite communications. We proposed to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation for operation at low pump intensities. This report outlines our progress toward these goals. Discussion of several technical details are left to the attached summary abstract.

  17. Visible light surface emitting semiconductor laser

    DOEpatents

    Olbright, Gregory R.; Jewell, Jack L.

    1993-01-01

    A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

  18. Particle-free semiconductor cutting using the water jet guided laser

    NASA Astrophysics Data System (ADS)

    Perrottet, Delphine; Spiegel, Akos; Wagner, Frank; Housh, Roy; Richerzhagen, Bernold; Manley, John

    2005-04-01

    For many years, wafer cutting has posed a challenge to laser-based cutting techniques because of the brittle nature of semiconductors and the exacting requirements for cleanliness. Since conventional laser cutting generates a strong heat-affected zone and a large amount of particles, abrasive sawing is currently the standard process for semiconductor wafer dicing. However, abrasive sawing can no longer fulfill the demands of new, emerging types of semiconductor devices like those based on thin wafers and compound semiconductors. New separation methods are investigated here. The water jet guided laser is a relatively recent technology that offers not only a significantly reduced heat-affected zone but also a cleaner wafer surface. This is due, first, to the water jet, which cools the material between the laser pulses and removes a significant amount of molten material generated by laser ablation. However, the system has recently been upgraded by adding a device that covers the entire wafer surface with a well-controlled thin water film throughout the cutting process. The few generated particles are thus kept in suspension and will not deposit on the wafer surface.

  19. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Injection lasers based on the AlGaAsSb system emitting at 1.6 μm

    NASA Astrophysics Data System (ADS)

    Virro, A. L.; Eliseev, P. G.; Lyuk, P. A.; Fridental, Ya K.; Khaller, Yu E.

    1988-11-01

    An experimental dependence of the threshold current density jth on the thickness of the active region was used to find the reduced threshold current density for AlGaAsSb (λ = 1.59μm, T = 295K) lasers: this density was 8 kA·cm-2·μm-1. The minimum threshold current was jth = 1.8 kA/cm2. Wide-contact lasers exhibited cw operation down to 175 K.

  20. Reactive Ion Etched Unstable and Stable Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Biellak, Stephen Alexander

    1995-01-01

    High power, diffraction-limited semiconductor laser diodes are desirable for numerous applications such as efficient solid state laser pumping, nonlinear frequency conversion, and free-space communication. In the past several years, wide-stripe diode lasers and laser arrays with powers of up to several watts have become commercially available, but the beam quality of these devices is generally poor due to filamentation, a nonlinear material effect that aberrates the output beam profile. An attractive alternative to these simple Fabry-Perot lasers is offered by unstable resonators, which have inherently large gain volumes and a cavity geometry that inhibits filamentation. Prototype unstable resonators with dry-etched cavity mirrors have recently been demonstrated to achieve near diffraction -limited operation at moderately high output powers. However, the lateral mode properties of unstable resonators have heretofore not been examined in detail, nor has a reliable, high-throughput mirror etch process been developed for these devices. In this work, we have developed a GaAs RIE etching technique using common process equipment that yields mirrors with RMS surface roughness of 3 to 5 nm. We have fabricated unstable resonators and have measured lateral M ^2 beam quality values as low as 1.25 at 300 mW single facet output power in high magnification devices. The impact of cavity geometry and processing techniques on device performance was studied, and the optimal parameters for high-brightness applications were determined. Nearly concentric stable-resonator diode lasers were also fabricated for the first time using this etching technique. These stable-resonators were observed to operate in lateral modes determined primarily by the physical resonator structure up to several times threshold, after which nonlinear effects dominated the cavity modes. Based on these measurements, a description of stable device behavior in terms of gain saturation was developed. Finally, a

  1. Study of the absorption coefficient in layers of a semiconductor laser heterostructure

    SciTech Connect

    Veselov, D A; Pikhtin, N A; Lyutetskiy, A V; Nikolaev, D N; Slipchenko, S O; Sokolova, Z N; Shamakhov, V V; Shashkin, I S; Voronkova, N V; Tarasov, I S

    2015-07-31

    A method of studying the absorption coefficient in layers of semiconductor lasers is proposed. Using lasers based on MOVPE-grown separate-confinement heterostructures with a broadened waveguide, the absorption coefficient is investigated under pulsed current pumping. It is found that when the pump current flows through the laser in question, an additional internal optical absorption arises in the heterostructure layers. It is shown that an increase in the pump current density up to 20 kA cm{sup -2} leads to an increase in absorption up to 2.5 cm{sup -1}. The feasibility of studying free-carrier absorption in the active region is demonstrated. (lasers)

  2. Analysis of broadly tunable coupled-cavity semiconductor lasers.

    PubMed

    Khan, Ferdous K; Cassidy, Daniel T

    2011-08-20

    We report on the spectral properties for above-threshold operation of broadly tunable, asymmetric multiple quantum well (AMQW), coupled-cavity InGaAsP/InP semiconductor diode lasers. We developed a traveling wave model to understand the mode selection that the lasers exhibit. We find that a weak, short external cavity (SXC) can be used to obtain single frequency operation on each longitudinal mode over the ∼100 nm tuning range of the uncoated AMQW coupled-cavity lasers. We measured the spectral properties of AMQW coupled-cavity lasers with and without an SXC. In a synthesized optical coherent optical tomography application, the use of an SXC with an AMQW coupled-cavity laser reduces the coherence length and hence enhances the performance of the AMQW coupled-cavity laser for optical coherence tomography applications. © 2011 Optical Society of America

  3. Optical Properties of Small Band Gap Semiconductors Subject to Laser Excitation. Nonlinear Infrared Properties of Semiconductors.

    DTIC Science & Technology

    1982-01-01

    the Ill-V semiconductors with large spin -orbit splitting . These included GaAs, G&Sb, InAs, AlSb as w ll as Ge. The theory was further extended to...includle Lhe effects of the spin orbit split -off valence band in publication 12. E. 7hory of Pump and Probe Experiments To develop an understanding of the...James and D. L. Smith, "Absorption of High-Intensity 002 Laser Light in p-Type Semiconductors with Small Spin -Orbit Splittings ", J. Appi. Phys. S2

  4. Laser-based displays: a review.

    PubMed

    Chellappan, Kishore V; Erden, Erdem; Urey, Hakan

    2010-09-01

    After the invention of lasers, in the past 50 years progress made in laser-based display technology has been very promising, with commercial products awaiting release to the mass market. Compact laser systems, such as edge-emitting diodes, vertical-cavity surface-emitting lasers, and optically pumped semiconductor lasers, are suitable candidates for laser-based displays. Laser speckle is an important concern, as it degrades image quality. Typically, one or multiple speckle reduction techniques are employed in laser displays to reduce speckle contrast. Likewise, laser safety issues need to be carefully evaluated in designing laser displays under different usage scenarios. Laser beam shaping using refractive and diffractive components is an integral part of laser displays, and the requirements depend on the source specifications, modulation technique, and the scanning method being employed in the display. A variety of laser-based displays have been reported, and many products such as pico projectors and laser televisions are commercially available already.

  5. 115 kHz tuning repetition rate ultrahigh-speed wavelength-swept semiconductor laser.

    PubMed

    Oh, W Y; Yun, S H; Tearney, G J; Bouma, B E

    2005-12-01

    We demonstrate an ultrahigh-speed wavelength-swept semiconductor laser using a polygon-based wavelength scanning filter. With a polygon rotational speed of 900 revolutions per second, a continuous wavelength tuning rate of 9200 nm/ms and a tuning repetition rate of 115 kHz were achieved. The wavelength tuning range of the laser was 80 nm centered at 1325 nm, and the average polarized output power was 23 mW.

  6. Extended-Cavity Semiconductor Wavelength-Swept Laser for Biomedical Imaging.

    PubMed

    Yun, S H; Boudoux, C; Pierce, M C; de Boer, J F; Tearney, G J; Bouma, B E

    2004-01-01

    We demonstrate a compact high-power rapidly swept wavelength tunable laser source based on a semiconductor optical amplifier and an extended-cavity grating filter. The laser produces excellent output characteristics for biomedical imaging, exhibiting >4-mW average output power, <0.06-nm instantaneous linewidth, and >80-dB noise extinction with its center wavelength swept over 100 nm at 1310 nm at variable repetition rates up to 500 Hz.

  7. Extended-Cavity Semiconductor Wavelength-Swept Laser for Biomedical Imaging

    PubMed Central

    Yun, S. H.; Boudoux, C.; Pierce, M. C.; de Boer, J. F.; Tearney, G. J.; Bouma, B. E.

    2010-01-01

    We demonstrate a compact high-power rapidly swept wavelength tunable laser source based on a semiconductor optical amplifier and an extended-cavity grating filter. The laser produces excellent output characteristics for biomedical imaging, exhibiting >4-mW average output power, <0.06-nm instantaneous linewidth, and >80-dB noise extinction with its center wavelength swept over 100 nm at 1310 nm at variable repetition rates up to 500 Hz. PMID:20640193

  8. Substrate-emitting semiconductor laser with a trapezoidal active region

    SciTech Connect

    Dikareva, N V; Nekorkin, S M; Karzanova, M V; Zvonkov, B N; Aleshkin, V Ya; Dubinov, A A; Afonenko, A A

    2014-04-28

    Semiconductor lasers with a narrow (∼2°) directional pattern in the planes both parallel and perpendicular to the p–n junction are fabricated. To achieve a low radiation divergence in the p–n junction plane, the active region in this plane was designed in the form of a trapezium. The narrow directional pattern in the plane perpendicular to the p–n junction was ensured by the use of a leaky mode, through which more than 90% of laser power was coupled out. (lasers)

  9. Spontaneously excited pulses in an optically driven semiconductor laser.

    PubMed

    Wieczorek, Sebastian; Lenstra, Daan

    2004-01-01

    In optically injected semiconductor lasers, intrinsic quantum noise alone, namely, the spontaneous emission and the shot noise, are capable of exciting intensity multipulses from a steady state operation. Noisy lasers exhibit self-pulsations in the locking region of the corresponding deterministic system. The interpulse time statistics are studied in parameter regions near k-homoclinic (Shilnikov) bifurcations where the corresponding deterministic model exhibits single-, double-, and triple-pulse excitability. These statistics differ significantly among each other, and they could be used to characterize regions of different multipulse excitability in a real laser device.

  10. Semiconductor laser theory with many-body effects

    SciTech Connect

    Haug, H.; Gayg, G.; Koch, S.W.

    1989-02-15

    A description of the electron-hole plasma of a semiconductor laser is developed that includes the many-body effects due to the Coulomb interactions. In particular, the plasma density-dependent band-gap renormalization, the broadening due to intraband scattering, and the Coulomb enhancement are included and evaluated for three- and two-dimensional semiconductor structures. Because of the short intraband scattering relaxation time one can eliminate the interband polarization adiabatically and at the same time introduce a hydrodynamic description of the interband kinetics. From this general formulation a diffusion equation for the carrier density is derived. The resulting ambipolar diffusion coefficient decreases with the laser intensity due to the reduction of the electron drift. The present semiclassical theory is completed by the laser field equations and by the addition of Langevin fluctuations.

  11. High Intensity Laser Interactions with Narrow Gap Semiconductors

    NASA Astrophysics Data System (ADS)

    Hasselback, Michael Peter

    1995-01-01

    Two-photon absorption in solids is a well known and thoroughly characterized nonlinear optical process. Higher order multi-photon absorption however, has received comparatively little study. In this dissertation, results of experiments with bulk, narrow gap semiconductors InSb and InAs are reported. By performing Z-scans and pump-probe measurements at different laser wavelengths and sample temperatures, various nonlinear optical processes are identified. Data obtained with InAs is consistent with photocarrier generation by three and four-photon absorption. It is believed this is the first direct evidence of four-photon absorption in a semiconductor. Leakage two-photon is observed with InSb at 15K. This novel effect arises from dynamic band un-blocking caused by laser heating of conduction electrons. All phenomena are excited with picosecond CO_2 laser pulses at irradiances below the material damage threshold. Physical models describing the observations are presented.

  12. Semiconductor laser devices having lateral refractive index tailoring

    DOEpatents

    Ashby, Carol I. H.; Hadley, G. Ronald; Hohimer, John P.; Owyoung, Adelbert

    1990-01-01

    A broad-area semiconductor laser diode includes an active lasing region interposed between an upper and a lower cladding layer, the laser diode further comprising structure for controllably varying a lateral refractive index profile of the diode to substantially compensate for an effect of junction heating during operation. In embodiments disclosed the controlling structure comprises resistive heating strips or non-radiative linear junctions disposed parallel to the active region. Another embodiment discloses a multi-layered upper cladding region selectively disordered by implanted or diffused dopant impurities. Still another embodiment discloses an upper cladding layer of variable thickness that is convex in shape and symmetrically disposed about a central axis of the active region. The teaching of the invention is also shown to be applicable to arrays of semiconductor laser diodes.

  13. Correlation dimension signature of wideband chaos synchronization of semiconductor lasers.

    PubMed

    Kane, D M; Toomey, J P; Lee, M W; Shore, K A

    2006-01-01

    Chaos data analysis has been performed on the chaotic output power time series data from a synchronized transmitter-receiver pair of semiconductor lasers. The system uses an asymmetric, bidirectional coupling configuration between the master (transmitter), which is a laser diode with optical feedback, and a stand-alone slave semiconductor laser. The correlation dimension of the chaotic time series has a minimum value of 4, which was obtained from high-bandwidth measurements. The correlation dimensions for both the master and the synchronized slave are identical when the cross-correlation coefficient of the synchronized chaos is above 0.9. These results establish correlation dimension analysis as an effective tool for the determination of the quality of wideband chaos synchronization.

  14. Phase instabilities in semiconductor lasers: A codimension-2 analysis

    NASA Astrophysics Data System (ADS)

    Gil, L.; Lippi, G. L.

    2014-11-01

    We compute the normal form description of a semiconductor laser near its threshold, with the sole assumption that the polarization be related to the electric field through the susceptibility (dependent on laser frequency and population inversion). We prove both analytically and numerically the possible existence of a phase-unstable regime, characterized by a periodic oscillation of the optical frequency and a constant intensity. This regime bears close resemblance to the mode-switching behavior, with constant total output power, experimentally observed in semiconductor lasers. In addition, our model predicts the appearance of a phase- and amplitude-turbulent regime, compatible with experimental observations. Both regimes are well known in fluid dynamics under the name Benjamin-Feir instability.

  15. Extreme events induced by collisions in a forced semiconductor laser.

    PubMed

    Walczak, Pierre; Rimoldi, Cristina; Gustave, Francois; Columbo, Lorenzo; Brambilla, Massimo; Prati, Franco; Tissoni, Giovanna; Barland, Stéphane

    2017-08-01

    We report on the experimental study of an optically driven multimode semiconductor laser with a 1 m cavity length. We observed a spatiotemporal regime where real-time measurements reveal very high-intensity peaks in the laser field. Such a regime, which coexists with the locked state and with stable phase solitons, is characterized by the emergence of extreme events that produce heavy tail statistics in the probability density function. We interpret the extreme events as collisions of spatiotemporal structures with opposite chirality. Numerical simulations of the semiconductor laser model, showing very similar dynamical behavior, substantiate our evidences and corroborate the description of interactions such as collisions between phase solitons and transient structures with different phase rotations.

  16. Femtosecond Laser Processing of Wide Bandgap Semiconductors and Their Applications

    NASA Astrophysics Data System (ADS)

    Phillips, Katherine Collett Furr

    This thesis explores the production, characterization, and water oxidation efficiency of wide bandgap semiconductors made through femtosecond-laser irradiation of various materials. Our investigation focuses on three main aspects: 1) producing titanium dioxide (TiO2) from titanium metal, 2) using our laser-made materials in a photoelectrochemical cell for water oxidation, and 3) utilizing the femtosecond laser to create a variety of other mixed metal oxides for further water oxidation studies and biological applications. We first discuss producing TiO2 and titanium nitride. We report that there is chemical selectivity at play in the femtosecond laser doping process so not all dopants in the surrounding atmosphere will necessarily be incorporated. We then show that the material made from laser-irradiation of titanium metal, when annealed, has a three-fold enhancement in overall water oxidation when irradiated with UV light. We attribute this enhancement through various material characterization methods to the creation of a more pure form of rutile TiO2 with less defects. We then present a variety of studies done with doping both TiO2 and other oxides with broadband photoelectrochemistry and offer that the dopant incorporation hurts the overall water oxidation rate. Lastly, we use the laser-treated titanium to test cell adhesion and viability. Our results demonstrate an ability to femtosecond-laser process semiconductors to produce materials that no one has made previously and study their properties using collaborations across chemistry and biology, yielding true interdisciplinary research.

  17. Confocal unstable-resonator semiconductor laser

    NASA Technical Reports Server (NTRS)

    Salzman, J.; Lang, R.; Yariv, A.; Larson, A.

    1986-01-01

    GaAs/GaAlAs heterostructure lasers with a monolithic confocal unstable resonator were demonstrated. The curved mirrors satisfying the confocal condition were fabricated by etching. Close to threshold, the lasers operate in a single lateral mode with a nearly collimated output beam. A single-lobe far-field intensity distribution as narrow as 1.9-deg full width at half maximum was measured.

  18. Record performance of electrical injection sub-wavelength metallic-cavity semiconductor lasers at room temperature.

    PubMed

    Ding, K; Hill, M T; Liu, Z C; Yin, L J; van Veldhoven, P J; Ning, C Z

    2013-02-25

    We demonstrate a continuous wave (CW) sub-wavelength metallic-cavity semiconductor laser with electrical injection at room temperature (RT). Our metal-cavity laser with a cavity volume of 0.67λ3 (λ = 1591 nm) shows a linewidth of 0.5 nm at RT, which corresponds to a Q-value of 3182 compared to 235 of the cavity Q, the highest Q under lasing condition for RT CW operation of any sub-wavelength metallic-cavity laser. Such record performance provides convincing evidences of the feasibility of RT CW sub-wavelength metallic-cavity lasers, thus opening a wide range of practical possibilities of novel nanophotonic devices based on metal-semiconductor structures.

  19. A theoretical model of the femtosecond laser ablation of semiconductors considering inverse bremsstrahlung absorption

    NASA Astrophysics Data System (ADS)

    Xiaohui, Lin; Chibin, Zhang; Weisong, Ren; Shuyun, Jiang; Quanhui, Ouyang

    2012-04-01

    The mechanism of the femtosecond laser ablation of semiconductors is investigated. The collision process of free electrons in a conduction band is depicted by the test particle method, and a theoretical model of nonequilibrium electron transport on the femtosecond timescale is proposed based on the Fokker—Planck equation. This model considers the impact of inverse bremsstrahlung on the laser absorption coefficient, and gives the expressions of electron drift and diffusion coefficients in the presence of screened Coulomb potential. Numerical simulations are conducted to obtain the nonequilibrium distribution function of the electrons. The femtosecond laser ablation thresholds are then calculated accordingly, and the results are in good agreement with the experimental results. This is followed by a discussion on the impact of laser parameters on the ablation of semiconductors.

  20. Semiconductor-based, large-area, flexible, electronic devices

    DOEpatents

    Goyal, Amit

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  1. Laser damage mechanisms in conductive widegap semiconductor films

    DOE PAGES

    Yoo, Jae-Hyuck; Menor, Marlon G.; Adams, John J.; ...

    2016-07-25

    Here, laser damage mechanisms of two conductive wide-bandgap semiconductor films - indium tin oxide (ITO) and silicon doped GaN (Si:GaN) were studied via microscopy, spectroscopy, photoluminescence (PL), and elemental analysis. Nanosecond laser pulse exposures with a laser photon energy (1.03 eV, 1064 nm) smaller than the conductive films bandgaps were applied and radically different film damage morphologies were produced. The laser damaged ITO film exhibited deterministic features of thermal degradation. In contrast, laser damage in the Si:GaN film resulted in highly localized eruptions originating at interfaces. For ITO, thermally driven damage was related to free carrier absorption and, for GaN,more » carbon complexes were proposed as potential damage precursors or markers.« less

  2. Laser damage mechanisms in conductive widegap semiconductor films

    DOE PAGES

    Yoo, Jae-Hyuck; Menor, Marlon G.; Adams, John J.; ...

    2016-07-25

    Here, laser damage mechanisms of two conductive wide-bandgap semiconductor films - indium tin oxide (ITO) and silicon doped GaN (Si:GaN) were studied via microscopy, spectroscopy, photoluminescence (PL), and elemental analysis. Nanosecond laser pulse exposures with a laser photon energy (1.03 eV, 1064 nm) smaller than the conductive films bandgaps were applied and radically different film damage morphologies were produced. The laser damaged ITO film exhibited deterministic features of thermal degradation. In contrast, laser damage in the Si:GaN film resulted in highly localized eruptions originating at interfaces. For ITO, thermally driven damage was related to free carrier absorption and, for GaN,more » carbon complexes were proposed as potential damage precursors or markers.« less

  3. Laser damage mechanisms in conductive widegap semiconductor films

    SciTech Connect

    Yoo, Jae-Hyuck; Menor, Marlon G.; Adams, John J.; Raman, Rajesh N.; Lee, Jonathan R. I.; Olson, Tammy Y.; Shen, Nan; Suh, Joonki; Demos, Stavros G.; Bude, Jeff; Elhadj, Selim

    2016-07-25

    Here, laser damage mechanisms of two conductive wide-bandgap semiconductor films - indium tin oxide (ITO) and silicon doped GaN (Si:GaN) were studied via microscopy, spectroscopy, photoluminescence (PL), and elemental analysis. Nanosecond laser pulse exposures with a laser photon energy (1.03 eV, 1064 nm) smaller than the conductive films bandgaps were applied and radically different film damage morphologies were produced. The laser damaged ITO film exhibited deterministic features of thermal degradation. In contrast, laser damage in the Si:GaN film resulted in highly localized eruptions originating at interfaces. For ITO, thermally driven damage was related to free carrier absorption and, for GaN, carbon complexes were proposed as potential damage precursors or markers.

  4. Metal-optic and Plasmonic Semiconductor-based Nanolasers

    NASA Astrophysics Data System (ADS)

    Lakhani, Amit Manmohan

    Over the past few decades, semiconductor lasers have relentlessly followed the path towards miniaturization. Smaller lasers are more energy efficient, are cheaper to make, and open up new applications in sensing and displays, among many other things. Yet, up until recently, there was a fundamental problem with making lasers smaller: purely semiconductor lasers couldn't be made smaller than the diffraction limit of light. In recent years, however, metal-based lasers have been demonstrated in the nanoscale that have shattered the diffraction limit. As optical materials, metals can be used to either reflect light (metal-optics) or convert light to electrical currents (plasmonics). In both cases, metals have provided ways to squeeze light beyond the diffraction limit. In this dissertation, I experimentally demonstrated one nanolaser based on plasmonic transduction and another laser based on metal-optic reflection. To create coherent plasmons, I designed a nanolaser based on a plasmonic bandgap defect state inside a surface plasmonic crystal. In a one-dimensional periodic semiconductor beam, I was able to confine surface plasmons by interrupting the periodicity of the crystal. These confined surface plasmons then underwent laser oscillations in effective mode volumes as small as 0.007 cubic wavelengths. At this electromagnetic volume, energy was squeezed 10 times smaller than those possible in similar photonic crystals that do not utilize metal. This demonstration should pave the way for achieving engineered nanolasers with deep-subwavelength mode volumes and enable plasmonic crystals to become attractive platforms for designing plasmons. After achieving large reductions in electromagnetic mode volumes, I switched to a metal-optics-based nanolaser design to further reduce the physical volumes of small light sources. The semiconductor nanopatch laser achieved laser oscillations with subwavelength-scale physical dimensions (0.019 cubic wavelengths) and effective mode

  5. N.G. Basov and early works on semiconductor lasers at P.N. Lebedev Physics Institute

    SciTech Connect

    Eliseev, P G

    2012-12-31

    A survey is presented of works on creation and investigation of semiconductor lasers during 1957 - 1977 at the P.N. Lebedev Physics Institute. Many of these works were initiated by N.G. Basov, starting from pre-laser time, when N.G. Basov and his coworkers formulated principal conditions of creation of lasers on interband transitions in semiconductors. Main directions of further works were diode lasers based on various materials and structures, their characteristics of output power, high-speed operation and reliability. (special issue devoted to the 90th anniversary of n.g. basov)

  6. Heterodyne applications of tunable semiconductor diode lasers

    NASA Technical Reports Server (NTRS)

    Sidney, B. D.

    1983-01-01

    Infrared tunable diode lasers were developed in the 1960s and have been a valuable radiation source for high resolution laboratory and in situ spectroscopy. Use of Pb-salt Tunable Diode Lasers (TDL) in heterodyne applications impose stringent requirements on the TDL not normally required for laboratory spectroscopy. A review will be made of progress associated with TDLs in such heterodyne applications. Areas addressed will include such items as lifetime, operating temperature, and factors affecting excess noise. The review will emphasize the experience at Langley Research Center, but will include material from other users. The Langley information will include a description and current status of the Laser Heterodyne Spectrometer experiment and atmospheric solar absorption data obtained from a groundbased heterodyne system.

  7. Synchronous characterization of semiconductor microcavity laser beam.

    PubMed

    Wang, T; Lippi, G L

    2015-06-01

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

  8. Synchronous characterization of semiconductor microcavity laser beam

    SciTech Connect

    Wang, T. Lippi, G. L.

    2015-06-15

    We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam’s tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

  9. Wavelength-resonant surface-emitting semiconductor laser

    DOEpatents

    Brueck, Steven R. J.; Schaus, Christian F.; Osinski, Marek A.; McInerney, John G.; Raja, M. Yasin A.; Brennan, Thomas M.; Hammons, Burrell E.

    1989-01-01

    A wavelength resonant semiconductor gain medium is disclosed. The essential feature of this medium is a multiplicity of quantum-well gain regions separated by semiconductor spacer regions of higher bandgap. Each period of this medium consisting of one quantum-well region and the adjacent spacer region is chosen such that the total width is equal to an integral multiple of 1/2 the wavelength in the medium of the radiation with which the medium is interacting. Optical, electron-beam and electrical injection pumping of the medium is disclosed. This medium may be used as a laser medium for single devices or arrays either with or without reflectors, which may be either semiconductor or external.

  10. Nonlinear Laser Spectroscopy Studies of Semiconductor Heterostructures

    DTIC Science & Technology

    1993-01-14

    AENTATION PAGE AD- A265 728 "Oft~ a "aq6 or ci" MW~s soo of M"~,ma~ ,, 11 49CAT ATI3. 44PONT trVP ANDOA*11 C3ViRfO Final Ronort I1,- Dec 8( j 4 AFCSR...93-13141 1. SUuuACT Eman IS wuin* 0F PAGIS 17. SAWW"T OLASSWICAT1O IL. 31Siiu7rY ýASSWICATION It. SEVJI’V CLASSWICATMN 26. UWTAT1O OF A &SSItACT OF alp...these materials may provide improved performance over silicon. In addition since they are a direct band gap semiconductor, there are also potential

  11. High-power MIXSEL: an integrated ultrafast semiconductor laser with 6.4 W average power.

    PubMed

    Rudin, B; Wittwer, V J; Maas, D J H C; Hoffmann, M; Sieber, O D; Barbarin, Y; Golling, M; Südmeyer, T; Keller, U

    2010-12-20

    High-power ultrafast lasers are important for numerous industrial and scientific applications. Current multi-watt systems, however, are based on relatively complex laser concepts, for example using additional intracavity elements for pulse formation. Moving towards a higher level of integration would reduce complexity, packaging, and manufacturing cost, which are important requirements for mass production. Semiconductor lasers are well established for such applications, and optically-pumped vertical external cavity surface emitting lasers (VECSELs) are most promising for higher power applications, generating the highest power in fundamental transverse mode (>20 W) to date. Ultrashort pulses have been demonstrated using passive modelocking with a semiconductor saturable absorber mirror (SESAM), achieving for example 2.1-W average power, sub-100-fs pulse duration, and 50-GHz pulse repetition rate. Previously the integration of both the gain and absorber elements into a single wafer was demonstrated with the MIXSEL (modelocked integrated external-cavity surface emitting laser) but with limited average output power (<200 mW). We have demonstrated the power scaling concept of the MIXSEL using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MIXSEL structure directly onto a CVD-diamond heat spreader. The simple straight cavity with only two components has generated 28-ps pulses at 2.5-GHz repetition rate and an average output power of 6.4 W, which is higher than for any other modelocked semiconductor laser.

  12. [A clinical observation of pericoronitis treatment with pulse semiconductor laser].

    PubMed

    Lu, Shan; Fang, Yuan

    2004-08-01

    In order to valuate the effect of pericoronitis treated with pulse semiconductor laser. As a treatment group, 24 ones drawn ramdomly from 48 cases of pericoronitis were given periodontal radiation, point-radiation therapy and pharmacotherapy as well. While another 24 cases as a contrast group were given pharmacotherapy only. On the 3rd day and the 5th day the degree of pain and restriction of mouth opening of the two groups were graded, contrasted and processed by Ridit statistics. Result, The therapy group gained more notable effect in pain-relieving and mouth-opening-improving than the contrast group. Because of no damage, handy and can be done easily, be definite in curative effect, Pulse semiconductor laser treatment pericoronitis deserves popularizing.

  13. Colorless WDM-PON based on a Fabry-Pérot laser diode and reflective semiconductor optical amplifiers for simultaneous transmission of bidirectional gigabit baseband signals and broadcasting signal.

    PubMed

    Pham, Thang Tien; Kim, Hyun-Seung; Won, Yong-Yuk; Han, Sang-Kook

    2009-09-14

    A novel WDM-PON system delivering bidirectional baseband data and broadcasting data is proposed and demonstrated. A subcarrier multiplexing signal is broadcasted to all users by modulating a broadband optical source based on a Fabry-Pérot laser diode. Reflective semiconductor optical amplifiers are used as colorless modulators for the baseband data at both optical line terminal and remote optical network units. Transmission performance including bit error rate of bidirectional gigabit data and error vector magnitude of broadcasting data of many optical channels is investigated. Additionally, the data rate for the broadcasting signal was improved by using an external modulator.

  14. Excitability in a quantum dot semiconductor laser with optical injection.

    PubMed

    Goulding, D; Hegarty, S P; Rasskazov, O; Melnik, S; Hartnett, M; Greene, G; McInerney, J G; Rachinskii, D; Huyet, G

    2007-04-13

    We experimentally analyze the dynamics of a quantum dot semiconductor laser operating under optical injection. We observe the appearance of single- and double-pulse excitability at one boundary of the locking region. Theoretical considerations show that these pulses are related to a saddle-node bifurcation on a limit cycle as in the Adler equation. The double pulses are related to a period-doubling bifurcation and occur on the same homoclinic curve as the single pulses.

  15. Refractory period of an excitable semiconductor laser with optical injection

    NASA Astrophysics Data System (ADS)

    Garbin, B.; Dolcemascolo, A.; Prati, F.; Javaloyes, J.; Tissoni, G.; Barland, S.

    2017-01-01

    Injection-locked semiconductor lasers can be brought to a neuronlike excitable regime when parameters are set close to the unlocking transition. Here we study experimentally the response of this system to repeated optical perturbations and observe the existence of a refractory period during which perturbations are not able to elicit an excitable response. The results are analyzed via simulations of a set of dynamical equations which reproduced adequately the experimental results.

  16. Excitability in semiconductor microring lasers: Experimental and theoretical pulse characterization

    SciTech Connect

    Gelens, L.; Coomans, W.; Van der Sande, G.; Verschaffelt, G.; Mashal, L.; Beri, S.; Danckaert, J.

    2010-12-15

    We characterize the operation of semiconductor microring lasers in an excitable regime. Our experiments reveal a statistical distribution of the characteristics of noise-triggered optical pulses that is not observed in other excitable systems. In particular, an inverse correlation exists between the pulse amplitude and duration. Numerical simulations and an interpretation in an asymptotic phase space confirm and explain these experimentally observed pulse characteristics.

  17. External cavity beam combining of 21 semiconductor lasers using SPGD.

    PubMed

    Montoya, Juan; Augst, Steven J; Creedon, Kevin; Kansky, Jan; Fan, Tso Yee; Sanchez-Rubio, Antonio

    2012-04-10

    Active coherent beam combining of laser oscillators is an attractive way to achieve high output power in a diffraction limited beam. Here we describe an active beam combining system used to coherently combine 21 semiconductor laser elements with an 81% beam combining efficiency in an external cavity configuration compared with an upper limit of 90% efficiency in the particular configuration of the experiment. Our beam combining system utilizes a stochastic parallel gradient descent (SPGD) algorithm for active phase control. This work demonstrates that active beam combining is not subject to the scaling limits imposed on passive-phasing systems.

  18. Analytical model of spin-polarized semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Gøthgen, Christian; Oszwałdowski, Rafał; Petrou, Athos; Žutić, Igor

    2008-07-01

    We formulate an analytical model for semiconductor lasers with injection (pump) of spin-polarized electrons, allowing us to systematically investigate different operating regimes. We demonstrate that the maximum threshold reduction by electrically pumped spin-polarized carriers is larger than previously thought possible and, surprisingly, can be enhanced by ultrafast spin relaxation of holes. We reveal how different modes of carrier recombination directly affect the threshold reduction. Neither spin-up nor spin-down electron populations are separately clamped (pinned) near the threshold, where such lasers can act as effective nonlinear filters of circularly polarized light, owing to their spin-dependent gain.

  19. Frequency beating between monolithically integrated semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Cao, Hongjun; Liu, Chiyu; Ling, Hai; Deng, Hui; Benavidez, Marcita; Smagley, Vladimir A.; Caldwell, Robert B.; Peake, Gregory M.; Smolyakov, Gennady A.; Eliseev, Petr G.; Osiński, Marek

    2005-01-01

    Optoelectronic integrated circuits incorporating a pair of optically independent large-cavity semiconductor ring lasers (SRLs), directional couplers, waveguides, Y-junction mixer, and photodetectors are demonstrated. Counterclockwise and clockwise output beams from the two SRLs are collected separately and mixed prior to detection. Frequency beating between modes of two SRLs is measured. The beat frequency is fine-tuned by an integrated Joule heater, designed for thermal control of the lasing wavelength. No signs of frequency lock-in in the vicinity of zero detuning are observed, which makes this structure a promising candidate for applications in ring laser gyros and optical rotation sensors.

  20. Sensitivity of quantum-dot semiconductor lasers to optical feedback.

    PubMed

    O'Brien, D; Hegarty, S P; Huyet, G; Uskov, A V

    2004-05-15

    The sensitivity of quantum-dot semiconductor lasers to optical feedback is analyzed with a Lang-Kobayashi approach applied to a standard quantum-dot laser model. The carriers are injected into a quantum well and are captured by, or escape from, the quantum dots through either carrier-carrier or phonon-carrier interaction. Because of Pauli blocking, the capture rate into the dots depends on the carrier occupancy level in the dots. Here we show that different carrier capture dynamics lead to a strong modification of the damping of the relaxation oscillations. Regions of increased damping display reduced sensitivity to optical feedback even for a relatively large alpha factor.

  1. High density semiconductor nanodots by direct laser fabrication

    NASA Astrophysics Data System (ADS)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    We report a direct method of fabricating high density nanodots on the GaAs(001) surfaces using laser irradiations on the surface. Surface images indicate that the large clumps are not accompanied with the formation of nanodots even though its density is higher than the critical density above which detrimental large clumps begin to show up in the conventional Stranski-Krastanov growth technique. Atomic force microscopy is used to image the GaAs(001) surfaces that are irradiated by high power laser pulses interferentially. The analysis suggests that high density quantum dots be fabricated directly on semiconductor surfaces.

  2. Thermal effects of pulsed pumping in semiconductor disk lasers

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Dai, Teli; Liang, Yiping; Fan, Siqiang; Zhang, Yu

    2012-11-01

    It has been demonstrated experimentally that pulsed pumping can significantly improve the thermal management in an optically-pumped semiconductor disk laser, and the output power of semiconductor disk lasers under pulsed pumping can be upgraded to times of those under continuous pumping. This paper presents numerical analysis of the thermal effects of pulsed pumping in semiconductor disk lasers, so to theoretically disclose the details of the thermal processes of pulsed pumping. In the simulation, the parabolic heat conduction equation, which is widely employed to describe the transient thermal transfer processes, is solved under cylindrical coordinates by the use of the finite element method, a periodic pump pulses train is assumed, and the maximum temperature rise in the multiple quantum wells active region is focused. The influences of the duty cycle, the repetition rate, and the pulse width of the pump pulses on the maximum temperature rise are investigated, and the results are compared with the case of continuous-wave pumping. Some simulation results are compared with reported data, and the theoretical results are in good agreement with the experiments.

  3. Toward continuous-wave operation of organic semiconductor lasers

    PubMed Central

    Sandanayaka, Atula S. D.; Matsushima, Toshinori; Bencheikh, Fatima; Yoshida, Kou; Inoue, Munetomo; Fujihara, Takashi; Goushi, Kenichi; Ribierre, Jean-Charles; Adachi, Chihaya

    2017-01-01

    The demonstration of continuous-wave lasing from organic semiconductor films is highly desirable for practical applications in the areas of spectroscopy, data communication, and sensing, but it still remains a challenging objective. We report low-threshold surface-emitting organic distributed feedback lasers operating in the quasi–continuous-wave regime at 80 MHz as well as under long-pulse photoexcitation of 30 ms. This outstanding performance was achieved using an organic semiconductor thin film with high optical gain, high photoluminescence quantum yield, and no triplet absorption losses at the lasing wavelength combined with a mixed-order distributed feedback grating to achieve a low lasing threshold. A simple encapsulation technique greatly reduced the laser-induced thermal degradation and suppressed the ablation of the gain medium otherwise taking place under intense continuous-wave photoexcitation. Overall, this study provides evidence that the development of a continuous-wave organic semiconductor laser technology is possible via the engineering of the gain medium and the device architecture. PMID:28508042

  4. Toward continuous-wave operation of organic semiconductor lasers.

    PubMed

    Sandanayaka, Atula S D; Matsushima, Toshinori; Bencheikh, Fatima; Yoshida, Kou; Inoue, Munetomo; Fujihara, Takashi; Goushi, Kenichi; Ribierre, Jean-Charles; Adachi, Chihaya

    2017-04-01

    The demonstration of continuous-wave lasing from organic semiconductor films is highly desirable for practical applications in the areas of spectroscopy, data communication, and sensing, but it still remains a challenging objective. We report low-threshold surface-emitting organic distributed feedback lasers operating in the quasi-continuous-wave regime at 80 MHz as well as under long-pulse photoexcitation of 30 ms. This outstanding performance was achieved using an organic semiconductor thin film with high optical gain, high photoluminescence quantum yield, and no triplet absorption losses at the lasing wavelength combined with a mixed-order distributed feedback grating to achieve a low lasing threshold. A simple encapsulation technique greatly reduced the laser-induced thermal degradation and suppressed the ablation of the gain medium otherwise taking place under intense continuous-wave photoexcitation. Overall, this study provides evidence that the development of a continuous-wave organic semiconductor laser technology is possible via the engineering of the gain medium and the device architecture.

  5. III-V Semiconductor Quantum Well Lasers and Related Optoelectronic Devices (On Silicon). Oxide-Defined Semiconductor Quantum Well Lasers and Optoelectrnic Devices: A1-Based III-V Native Oxides

    DTIC Science & Technology

    1992-05-01

    crystal growth (EMCORE reactor), and our NSF MRL has supported our TEM and SIMS analyses, which are spread throughout much of the work reported here. 10...AIGa .,As-GaAs quantum well heterostruct’ires two -600 A Al0.2 Ga,, As waveguide (WG) layers. Then a (QWHs) to suppress the effectr of alloy clu;tering...8217 the use thick (-0.5 um) AlAs p-type upper confining layer is of AlAs layers in QWHs has becomae cuite common in lasers grown, followed by the growth

  6. Tunable semiconductor laser with an acousto-optic filter in an external fibre cavity

    SciTech Connect

    Andreeva, E V; Mamedov, D S; Ruenkov, A A; Shramenko, M V; Magdich, L N; Yakubovich, S D

    2006-04-30

    A tunable semiconductor laser with a laser amplifier based on a double-pass superluminescent diode as an active element and an acousto-optic filter in an external fibre cavity as a selective element is investigated. A continuous spectral tuning is achieved in a band of width 60 nm centered at a wavelength of 845 nm and the 'instant' linewidth below 0.05 nm is obtained. The sweep frequency within the tuning range achieves 200 Hz. The cw power at the output of a single-mode fibre was automatically maintained constant at the level up to 1.5 mW. (lasers and amplifiers)

  7. Ultrashort pulse laser slicing of semiconductor crystal

    NASA Astrophysics Data System (ADS)

    Kim, Eunho; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Miura, Kiyotaka

    2016-07-01

    Meanwhile, by the convention wire-saw technique, it is difficult to slice off a thin wafer from bulk SiC crystal without the reserving space for cutting. In this study, we have achieved exfoliation of 4H-SiC single crystal by femtosecond laser induced slicing method. By using this, the exfoliated surface with the root-mean-square roughness of 3 μm and the cutting-loss thickness smaller than 30 μm was successfully demonstrated. We have also observed the nanostructure on the exfoliated surface in SiC crystal.

  8. Liquid Contact Luminescence from Semiconductor Laser Materials

    DTIC Science & Technology

    1997-01-09

    Young, P.S. Zory, and D.P. Bour, Layer Diodes and Applications, Kurt I. Linden , Prasad R. Akkapeddi, Editors, Proc. SPIE 2682, 136 (1996). 129 130...Grove, P.S. Zory, H.K. Choi, and G.W. Turner, Laser Diodes and Applications, Kurt L Linden , Prasad R. Akkapeddi, Editors, Proc. SPIE 2382, 244 (1995...equivalent circuit model developed for PAL is shown in Figure 2-13. Cox CdI . Rsod~n Rf D iode j ,h10o Figure 2-13. Schematic diagram of the PAL

  9. Single-sideband photonic microwave generation with an optically injected quantum-dot semiconductor laser.

    PubMed

    Chen, Chih-Ying; Cheng, Chih-Hao; Lin, Fan-Yi

    2016-12-26

    We studied single-sideband (SSB) photonic microwave generation with a high sideband rejection ratio (SRR) based on the period-one dynamical states of an optically injected quantum-dot (QD) semiconductor laser and demonstrated that the SSB signals have SRRs of approximately 15 dB higher than those generated with a conventional quantum-well semiconductor laser under conditions of optimal microwave power. The enhancement of SRR in the QD laser, which is important in mitigating the power penalty effect in applications such as radio-over-fiber optical communications, could be primarily attributed to a lower carrier decay rate in the dots, smaller linewidth enhancement factor, and reduced photon decay rate.

  10. Semiconductor-based optical refrigerator

    DOEpatents

    Epstein, Richard I.; Edwards, Bradley C.; Sheik-Bahae, Mansoor

    2002-01-01

    Optical refrigerators using semiconductor material as a cooling medium, with layers of material in close proximity to the cooling medium that carries away heat from the cooling material and preventing radiation trapping. In addition to the use of semiconducting material, the invention can be used with ytterbium-doped glass optical refrigerators.

  11. rf-microwave switches based on reversible semiconductor-metal transition of VO2 thin films synthesized by pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Dumas-Bouchiat, F.; Champeaux, C.; Catherinot, A.; Crunteanu, A.; Blondy, P.

    2007-11-01

    Microwave switching devices based on the semiconductor-metal transition of VO2 thin films were developped on two types of substrates (C-plane sapphire and SiO2/Si), and in both shunt and series configurations. Under thermal activation, the switches achieved up to 30-40dB average isolation of the radio-frequency (rf) signal on 500MHz -35GHz frequency band with weak insertion losses. These VO2-based switches can be electrically activated with commutation times less than 100ns, which make them promising candidates for realizing efficient and simple rf switches.

  12. Estimation of Frequency Noise in Semiconductor Lasers Due to Mechanical Thermal Noise

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We evaluate mechanical thermal noise in semiconductor lasers, applying a methodology developed for fixed-spacer cavities for laser frequency stabilization. Our simple model determines an underlying fundamental limit for the frequency noise of free-running semiconductor laser, and provides a framework: where the noise may be potentially reduced with improved design.

  13. Estimation of Frequency Noise in Semiconductor Lasers Due to Mechanical Thermal Noise

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We evaluate mechanical thermal noise in semiconductor lasers, applying a methodology developed for fixed-spacer cavities for laser frequency stabilization. Our simple model determines an underlying fundamental limit for the frequency noise of free-running semiconductor laser, and provides a framework: where the noise may be potentially reduced with improved design.

  14. Coherence switching of a vertical-cavity semiconductor-laser for multimode biomedical imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cao, Hui; Knitter, Sebastian; Liu, Changgeng; Redding, Brandon; Khokha, Mustafa Kezar; Choma, Michael Andrew

    2017-02-01

    Speckle formation is a limiting factor when using coherent sources for imaging and sensing, but can provide useful information about the motion of an object. Illumination sources with tunable spatial coherence are therefore desirable as they can offer both speckled and speckle-free images. Efficient methods of coherence switching have been achieved with a solid-state degenerate laser, and here we demonstrate a semiconductor-based degenerate laser system that can be switched between a large number of mutually incoherent spatial modes and few-mode operation. Our system is designed around a semiconductor gain element, and overcomes barriers presented by previous low spatial coherence lasers. The gain medium is an electrically-pumped vertical external cavity surface emitting laser (VECSEL) with a large active area. The use of a degenerate external cavity enables either distributing the laser emission over a large ( 1000) number of mutually incoherent spatial modes or concentrating emission to few modes by using a pinhole in the Fourier plane of the self-imaging cavity. To demonstrate the unique potential of spatial coherence switching for multimodal biomedical imaging, we use both low and high spatial coherence light generated by our VECSEL-based degenerate laser for imaging embryo heart function in Xenopus, an important animal model of heart disease. The low-coherence illumination is used for high-speed (100 frames per second) speckle-free imaging of dynamic heart structure, while the high-coherence emission is used for laser speckle contrast imaging of the blood flow.

  15. Comparison of thermal management techniques for semiconductor disk lasers

    NASA Astrophysics Data System (ADS)

    Giet, S.; Kemp, A. J.; Burns, D.; Calvez, S.; Dawson, M. D.; Suomalainen, S.; Harkonen, A.; Guina, M.; Okhotnikov, O.; Pessa, M.

    2008-02-01

    Semiconductor Disk Lasers (SDLs) are compact lasers suitable for watt to multi-watt direct generation in the 670- 2350nm waveband and frequency-doubled operation in the ultraviolet and visible regions. This is, however, critically dependent on the thermal management strategy used as, in this type of laser, the pump is absorbed over micrometer lengths and the gain and loss are temperature sensitive. In this paper, we compare the two heat dissipation techniques that have been successfully deployed to-date: the "thin device" approach where the semiconductor active mirror is bonded onto a heatsink and its substrate subsequently removed, and the "heatspreader" technique where a high thermal conductivity platelet is directly bonded onto the active part of the unprocessed epilayer. We show that for SDLs emitting at 1060nm with pump spots of ~80µm diameter, the heatspreader approach outperforms the thin-device alternative, with the best results being obtained with a diamond heatspreader. Indeed, the thermal resistances are measured to be 4.9, 10.4 and 13.0 K/W for diamond-bonded, SiC-bonded and flip-chip devices respectively. It is also observed, as expected, that the thermal management strategy indirectly affects the optimum output coupling and thus the overall performance of these lasers.

  16. Dynamic single-mode semiconductor lasers with a distributed reflector

    NASA Astrophysics Data System (ADS)

    Suematsu, Y.; Arai, S.; Kishino, K.

    1983-03-01

    Recent progress in dynamic single-mode (DSM) semiconductor lasers in the wavelength of 1.5-1.6 microns are reviewed, and the basic principle of DSM operation is given. Study of the DSM laser is originated for application to wide-band optical-fiber communication in the lowest loss wavelength region of 1.5 to 1.65 microns. A DSM laser consists of a mode-selective resonator and a transverse-mode-controller waveguide, as in the narrow-striped distributed-Bragg-reflector (DBR) laser, so as to maintain a fixed axial mode under rapid direct modulation. The technology of monolithic integration for optical circuits is applied to realize some DSM lasers. Structures, static and dynamic characteristics of lasing wavelength, output power, and reliability of state-of-the-art DSM lasers are reviewed. Dynamic spectral width of 0.3 nm, output power of a few milliwatts, and reliability over a few thousand hours are reported for experimental DSM lasers.

  17. Dynamic single-mode semiconductor lasers with a distributed reflector

    SciTech Connect

    Suematsu, Y.; Arai, S.; Kishino, K.

    1983-03-01

    Recent progress in dynamic single-mode (DSM) semiconductor lasers in the wavelength of 1.5-1.6 microns are reviewed, and the basic principle of DSM operation is given. Study of the DSM laser is originated for application to wide-band optical-fiber communication in the lowest loss wavelength region of 1.5 to 1.65 microns. A DSM laser consists of a mode-selective resonator and a transverse-mode-controller waveguide, as in the narrow-striped distributed-Bragg-reflector (DBR) laser, so as to maintain a fixed axial mode under rapid direct modulation. The technology of monolithic integration for optical circuits is applied to realize some DSM lasers. Structures, static and dynamic characteristics of lasing wavelength, output power, and reliability of state-of-the-art DSM lasers are reviewed. Dynamic spectral width of 0.3 nm, output power of a few milliwatts, and reliability over a few thousand hours are reported for experimental DSM lasers. 120 references.

  18. Modulation Response of a Long-Cavity, Gain-Levered Quantum-Dot Semiconductor Laser - Postprint

    DTIC Science & Technology

    2014-01-27

    of self-injected quantum-dot semiconductor diode lasers ,” IEEE J. Sel. Top. Quantum Electron. 19(4), 1900812 (2013). 7. M. Asada, Y. Mitamoto, and Y...capacity of existing semiconductor laser material structures by simply adding a single feature to a device’s electrical contact layout. Another...AFRL-RY-WP-TP-2014-0295 MODULATION RESPONSE OF A LONG-CAVITY, GAIN- LEVERED QUANTUM-DOT SEMICONDUCTOR LASER -POSTPRINT Nicholas G. Usechak

  19. Reliability of high-power semiconductor laser arrays

    NASA Astrophysics Data System (ADS)

    Kung, Hsing H.; Craig, Richard R.; Zucker, Erik P.; Li, Benjamin; Scifres, Donald R.

    1992-10-01

    The reliability of continuously operating (cw) high power laser arrays is a critical factor for the acceptance of these devices in a wide range of applications. Extensive investigation into the reliability of semiconductor lasers has led to an improved understanding of failure mechanisms such as material defects, mirror damage and solder related failures as well as to methods which significantly suppress the occurrence of catastrophic failure. Furthermore, as a result of material quality improvements, laser arrays exhibit very low gradual degradation for high power operation up to 2 Watts cw. Long term lifetest data shows that the projected medium life at room temperature of such devices exceed 100,000 hours at 2 W cw.

  20. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1987-01-01

    A 25 megabit/sec direct detection optical communication system that used Q=4 PPM signalling was constructed and its performance measured under laboratory conditions. The system used a single-mode AlGaAs laser diode transmitter and low noise silicon avalanche photodiode (APD) photodetector. Comparison of measured performance with the theoretical revealed that modeling the APD output as a Gaussian process under conditions of negligible background radiation and low (less than 10 to the -12 power A) APD bulk leakage currents leads to substantial underestimates of optimal APD gain to use and overestimates of system bit error probability. A procedure is given to numerically compute system performance which uses the more accurate Webb's Approximation of the exact Conradi distribution for the APD ouput signal that does not require excessive amounts of computer time (a few minutes of VAX 8600 CPU time per system operating point). Examples are given which illustrate the breakdown of the Gaussian approximation in assessing system performance. This system achieved a bit error probability of 10 to the -6 power at a received signal energy corresponding to an average of 60 absorbed photons/bit and optimal APD gain of 700.

  1. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1988-01-01

    Slot timing recovery in a direct detection optical PPM communication system can be achieved by processing the photodetector waveform with a nonlinear device whose output forms the input to a phase lock group. The choice of a simple transition detector as the nonlinearity is shown to give satisfactory synchronization performance. The rms phase error of the recovered slot clock and the effect of slot timing jitter on the bit error probability were directly measured. The experimental system consisted of an AlGaAs laser diode (lambda = 834 nm) and a silicon avalanche photodiode (APD) photodetector and used Q=4 PPM signaling operated at a source data rate of 25 megabits/second. The mathematical model developed to characterize system performance is shown to be in good agreement with actual performance measurements. The use of the recovered slot clock in the receiver resulted in no degradation in receiver sensitivity compared to a system with perfect slot timing. The system achieved a bit error probability of 10 to the minus 6 power at received signal energies corresponding to an average of less than 60 detected photons per information bit.

  2. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

    NASA Astrophysics Data System (ADS)

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-07-01

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

  3. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

    PubMed Central

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-01-01

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems. PMID:27431769

  4. Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation.

    PubMed

    Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

    2016-07-19

    Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems.

  5. Design, Modeling And Simulation Of Nanoscale Optoelectronic Devices: Semiconductor Nano-Lasers And Plasmonic Waveguides

    NASA Astrophysics Data System (ADS)

    Li, Debin

    This thesis summarizes the research work carried out on design, modeling and simulation of semiconductor nanophotonic devices. The research includes design of nanowire (NW) lasers, modeling of active plasmonic waveguides, design of plasmonic nano-lasers, and design of all-semiconductor plasmonic systems. For the NW part, a comparative study of electrical injection in the longitudinal p-i-n and coaxial p-n core-shell NWs was performed. It is found that high density carriers can be efficiently injected into and confined in the core-shell structure. The required bias voltage and doping concentrations in the core-shell structure are smaller than those in the longitudinal p-i-n structure. A new device structure with core-shell configuration at the p and n contact regions for electrically driven single NW laser was proposed. Through a comprehensive design trade-off between threshold gain and threshold voltage, room temperature lasing has been proved in the laser with low threshold current and large output efficiency. For the plasmonic part, the propagation of surface plasmon polariton (SPP) in a metal-semiconductor-metal structure where semiconductor is highly excited to have an optical gain was investigated. It is shown that near the resonance the SPP mode experiences an unexpected giant modal gain that is 1000 times of the material gain in the semiconductor and the corresponding confinement factor is as high as 105. The physical origin of the giant modal gain is the slowing down of the average energy propagation in the structure. Secondly, SPP modes lasing in a metal-insulator-semiconductor multi-layer structure was investigated. It is shown that the lasing threshold can be reduced by structural optimization. A specific design example was optimized using AlGaAs/GaAs/AlGaAs single quantum well sandwiched between silver layers. This cavity has a physical volume of 1.5x10-4 lambda 03 which is the smallest nanolaser reported so far. Finally, the all-semiconductor based

  6. Efficient gas lasers pumped by double-discharge circuits with semiconductor opening switch

    NASA Astrophysics Data System (ADS)

    Panchenko, Alexei N.; Tarasenko, Victor F.

    2012-01-01

    A review of applications of double-discharge circuits based on generators with inductive energy storage (IES) and semiconductor opening switches (SOS) for efficient excitation of different gas lasers is presented. Using a pre-pulse-sustainer circuit technique based on inductive energy storage and semiconductor opening switch generators allows the formation of a pre-pulse with high amplitude and short rise-time and provides a sharp increase of discharge current which significantly improves discharge stability and life-time of the volume discharge in gas mixtures containing halogens. A pre-pulse with high pumping power forms a high-density discharge plasma and an inversion population in gas mixtures under study within ∼10 ns and provides both early onset of lasing and conditions for efficient excitation of an active medium from the storage capacitor. As a result, pulse duration, output energy and efficiency of the lasers under study were improved.

  7. Modeling a semiconductor laser with an intracavity atomic absorber

    SciTech Connect

    Masoller, C.; Vilaseca, R.; Oria, M.

    2009-07-15

    The dynamics of a semiconductor laser with an intracavity atomic absorber is studied numerically. The study is motivated by the experiments of Barbosa et al. [Opt. Lett. 32, 1869 (2007)], using a semiconductor junction as an active medium, with its output face being antireflection coated, and a cell containing cesium vapor placed in a cavity that was closed by a diffraction grating (DG). The DG allowed scanning the lasing frequency across the D{sub 2} line in the Cs spectrum, and different regimes such as frequency bistability or dynamic instability were observed depending on the operating conditions. Here we propose a rate-equation model that takes into account the dispersive losses and the dispersive refractive index change in the laser cavity caused by the presence of the Cs vapor cell. These effects are described through a modification of the complex susceptibility. The numerical results are found to be in qualitative good agreement with some of the observations; however, some discrepancies are also noticed, which can be attributed to multi-longitudinal-mode emission in the experiments. The simulations clearly show the relevant role of the Lamb dips and crossover resonances, which arise on top of the Doppler-broadened D{sub 2} line in the Cs spectrum, and are due to the forward and backward intracavity fields interacting resonantly with the Cs atoms. When the laser frequency is locked in a dip, a reduction in the frequency noise and of the intensity noise is demonstrated.

  8. Ultrahigh-power semiconductor lasers and their applications

    NASA Astrophysics Data System (ADS)

    He, Xiaoguang; Srinivasan, Swaminathan T.; Gupta, Shantanu; Patel, Rushikesh M.

    1998-08-01

    High power semiconductor laser diodes have found their place in a wide variety of markets such as printing, pumping of solid state lasers, illumination, medical diagnosis, surgery, spectroscopy and material processing. In the past two years, the performance of the commercial available multi-mode semiconductor laser diodes has been elevated to a ultra high power level (continuous wave (CW) power density higher than 15 mW/micrometers -aperture for single emitter devices and 10 mW/micrometers -aperture per cm wide bar for monolithic arrays) as the result of breakthrough in device design, processing and packaging. We present in this paper record setting performance of these ultra high power devices in terms of CW power (> 10.6 W from 100 micrometers aperture, > 180 W from 1 cm wide array) and efficiency (wall plug-in efficiency 59%, differential quantum efficiency 87%). Reliability tests of these ultra high power devices indicates that these devices have equivalent to or better reliability than conventional lower power commercial devices. We will discuss the significance of these devices in enabling new applications and empowering current applications.

  9. High-speed modelocked semiconductor lasers and applications in coherent photonic systems

    NASA Astrophysics Data System (ADS)

    Lee, Wangkuen

    1.55-mum high-speed modelocked semiconductor lasers are theoretically and experimentally studied for various coherent photonic system applications. The modelocked semiconductor lasers (MSLs) are designed with high-speed (>5 GHz) external cavity configurations utilizing monolithic two-section curved semiconductor optical amplifiers. By exploiting the saturable absorber section of the monolithic device, passive or hybrid mode-locking techniques are used to generate short optical pulses with broadband optical frequency combs. Laser frequency stability is improved by applying the Pound-Drever-Hall (PDH) frequency stabilization technique to the MSLs. The improved laser performance after the frequency stabilization (a frequency drifting of less than 350 MHz), is extensively studied with respect to the laser linewidth (˜ 3 MHz), the relative intensity noise (RIN) (< -150 dB/Hz), as well as the modal RIN (˜ 3 dB reduction). MSL to MSL, and tunable laser to MSL synchronization is demonstrated by using a dual-mode injection technique and a modulation sideband injection technique, respectively. Dynamic locking behavior and locking bandwidth are experimentally and theoretically studied. Stable laser synchronization between two MSLs is demonstrated with an injection seed power on the order of a few microwatt. Several coherent heterodyne detections based on the synchronized MSL systems are demonstrated for applications in microwave photonic links and ultra-dense wavelength division multiplexing (UD-WDM) system. In addition, efficient coherent homodyne balanced receivers based on synchronized MSLs are developed and demonstrated for a spectrally phase-encoded optical CDMA (SPE-OCDMA) system.

  10. Power scalable semiconductor disk lasers for frequency conversion and mode-locking

    SciTech Connect

    Okhotnikov, O G

    2008-12-31

    The semiconductor disk laser, a relatively novel type of light oscillators, is now under intensive development. These lasers produce an excellent beam quality in conjunction with a scalable output power. This paper presents recent achievements in power scalability, mode-locking and frequency conversion with optically-pumped semiconductor disk lasers. A novel concept for power scaling described here allows the thermal load of the gain material to be reduced, increasing the threshold of rollover and extending the capability for boosting the output power without degradation in the beam quality. The proposed technique is based on the multiple gain scheme. The total power of over 8 W was achieved in dual-gain configuration, while one-gain lasers could produce separately up to 4 W, limited by the thermal rollover of the output characteristics. The results show that the reduced thermal load to a gain element in a dual-gain cavity allows extending the range of usable pump powers boosting the laser output. Orange-red radiation required for a number of challenging applications can be produced through frequency-doubling using a GaInNAs/GaAs laser. Using such a disk laser operating at a fundamental wavelength of 1224 nm, we demonstrate an output power of 2.68 W in the visible region with an optical-to-optical conversion efficiency of 7.4%. The frequency-converted signal could be launched into a single-mode optical fibre with 70%-78% coupling efficiency, demonstrating good beam quality for the visible radiation. Using a Fabry-Perot glass etalon, the emission wavelength could be tuned over an 8-nm spectral range. We report on optically-pumped disk lasers passively mode-locked with a semiconductor saturable-absorber mirror. The potential of harmonic mode-locking in producing pulse trains at multigigahertz repetition rates has been explored. The mode-locked disk laser is investigated for different designs of the gain medium that allow bistable mode-locking to be controlled. An

  11. Investigation of Semiconductor Lasers for Wideband Recording

    DTIC Science & Technology

    1975-03-01

    AFB NT 13441. D D C Laboratory Directors’ Fund No. 01737406 Rome Air Development Center Air Force Systems Comnand «Sriffiss Air Force Base , New...N/if0 H DULC I«. DISTRIBUTION STATEMENT fo/«M«R«p«»0 M V Distribution limited to U. S. Gov’t agenclea only; test and evaluation; March 1975...exhibited faintly detectable modulation and high base fog levels when exposed and developed in the same manner as AGFA 10E75. Experiments with

  12. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation

    NASA Astrophysics Data System (ADS)

    Wan, W. J.; Li, H.; Zhou, T.; Cao, J. C.

    2017-03-01

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification.

  13. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation.

    PubMed

    Wan, W J; Li, H; Zhou, T; Cao, J C

    2017-03-08

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification.

  14. Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation

    PubMed Central

    Wan, W. J.; Li, H.; Zhou, T.; Cao, J. C.

    2017-01-01

    Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification. PMID:28272492

  15. High Efficiency, Room Temperature Mid-Infrared Semiconductor Laser Development for IR Countermeasures

    DTIC Science & Technology

    2009-05-01

    PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) AFOSR/NE 875 N. Randolph St. Rm. 3112 Arlington, VA...through December of 2007, the work was expanded to include the development of plasma etch processes in an Oxford Instruments 100 ICP 180 System for ZnO...characterization and fabrication of antimonide-based semiconductor lasers for infrared applications. The fabrication of the devices continued to be done

  16. Exploring multistability in semiconductor ring lasers: theory and experiment.

    PubMed

    Gelens, L; Beri, S; Van der Sande, G; Mezosi, G; Sorel, M; Danckaert, J; Verschaffelt, G

    2009-05-15

    We report the first experimental observation of multistable states in a single-longitudinal mode semiconductor ring laser. We show how the operation of the device can be steered to either monostable, bistable, or multistable dynamical regimes in a controlled way. We observe that the dynamical regimes are organized in well-reproducible sequences that match the bifurcation diagrams of a two-dimensional model. By analyzing the phase space in this model, we predict how the stochastic transitions between multistable states take place and confirm it experimentally.

  17. An electrically injected rolled-up semiconductor tube laser

    SciTech Connect

    Dastjerdi, M. H. T.; Djavid, M.; Mi, Z.

    2015-01-12

    We have demonstrated electrically injected rolled-up semiconductor tube lasers, which are formed when a coherently strained InGaAs/InGaAsP quantum well heterostructure is selectively released from the underlying InP substrate. The device exhibits strong coherent emission in the wavelength range of ∼1.5 μm. A lasing threshold of ∼1.05 mA is measured for a rolled-up tube with a diameter of ∼5 μm and wall thickness of ∼140 nm at 80 K. The Purcell factor is estimated to be ∼4.3.

  18. DBR-free optically pumped semiconductor disk lasers

    NASA Astrophysics Data System (ADS)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

    2015-03-01

    Optically pumped semiconductor disk lasers (SDLs) provide high beam quality with high average-power power at designer wavelengths. However, material choices are limited by the need for a distributed Bragg reflector (DBR), usually monolithically integrated with the active region. We demonstrate DBR-free SDL active regions, which have been lifted off and bonded to various transparent substrates. For an InGaAs multi-quantum well sample bonded to a diamond window heat spreader, we achieved CW lasing with an output power of 2 W at 1150 nm with good beam quality.

  19. Predictability of extreme intensity pulses in optically injected semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Alvarez, Nuria Martinez; Borkar, Saurabh; Masoller, Cristina

    2017-06-01

    The predictability of extreme intensity pulses emitted by an optically injected semiconductor laser is studied numerically, by using a well-known rate equation model. We show that symbolic ordinal time-series analysis allows to identify the patterns of intensity oscillations that are likely to occur before an extreme pulse. The method also gives information about patterns which are unlikely to occur before an extreme pulse. The specific patterns identified capture the topology of the underlying chaotic attractor and depend on the model parameters. The methodology proposed here can be useful for analyzing data recorded from other complex systems that generate extreme fluctuations in their output signals.

  20. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Simple pulsed semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Hulicius, E.; Abrahám, A.; Sĭmeček, T.

    1988-11-01

    A brief review is given of the main characteristics of pulsed GaAlAs/GaAs lasers made in Czechoslovakia. A description is given of laser structures with large optical cavities and their electrical, optical, and service life characteristics are reported.

  1. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Computer model for quasioptic waveguide lasers

    NASA Astrophysics Data System (ADS)

    Wenzel, H.; Wünsche, H. J.

    1988-11-01

    A description is given of a numerical model of a semiconductor laser with a quasioptic waveguide (index guide). This model can be used on a personal computer. The model can be used to find the radiation field distributions in the vertical and lateral directions, the pump currents at the threshold, and also to solve dynamic rate equations.

  2. Compact confocal readout system for three-dimensional memories using a laser-feedback semiconductor laser.

    PubMed

    Nakano, Masaharu; Kawata, Yoshimasa

    2003-08-01

    We present a compact confocal readout system for three-dimensional optical memories that uses the thresholding property of a semiconductor laser for feedback light. The system has higher axial resolution than a conventional confocal system with a pinhole. We demonstrate readout results for data recorded in two recording layers with the developed system.

  3. Theory of semiconductor laser cooling at low temperatures

    NASA Astrophysics Data System (ADS)

    Rupper, G.; Kwong, N. H.; Binder, R.

    2006-02-01

    On the road toward experimental realization of laser-induced cooling of semiconductors, theoretical investigations are necessary for a detailed understanding of the microscopic phenomena underlying the cooling process, and for a prediction of optimal parameter regimes where efficient cooling could be expected. A recent realistic theory for cooling of bulk GaAs by Sheik-Bahae and Epstein has focused on the high-temperature regime, where the cooling process involves absorption of and luminescence from an electron-hole plasma. Using a microscopic many-particle theory, we extend the Sheik-Bahae Epstein approach to the low-temperature regime, where excitonic effects, i.e. effects of bound electron hole pairs in quasi-thermal equilibrium with correlated unbound pairs (i.e. the plasma) become important. We use a diagrammatic approach that is non-perturbative in the Coulomb interaction and contains effects of phase-space filling, single-particle renormalization in a partially ionized plasma, and screening. We ensure that our theory contains the relevant limiting cases for (partial) ionization in the low-density regime (Saha equation and Beth-Uhlenbeck formula) as well as the high density regime (Mott transition). Based on our microscopic theory for absorption and luminescence in the quasi-thermal equilibrium regime, we present a detailed study of cooling criteria at low temperature, focusing mainly on the temperature regime between 5K and 100K. In particular, we discuss the transition from the high temperature regime dominated by absorption in the e-h continuum to the low-temperature regime dominated by resonant exciton absorption.

  4. Slow axis collimation lens with variable curvature radius for semiconductor laser bars

    NASA Astrophysics Data System (ADS)

    Xiong, Ling-Ling; Cai, Lei; Zheng, Yan-Fang; Liu, Hui; Zhang, Pu; Nie, Zhi-Qiang; Liu, Xing-Sheng

    2016-03-01

    Based on Snell's law and the constant phase in the front of optical field, a design method of the slow axis collimation lens with variable curvature radius is proposed for semiconductor laser bars. Variable radius of the collimator is designed by the transmission angle, and it is demonstrated that the collimator has good beam collimation ability by material with low refractive index. Resorting to the design thought of finite element method, the surface of the collimator has been divided, and it is feasible to be fabricated. This method is applied as an example in collimation of a 976 nm semiconductor laser bar. 6 mrad divergence angle of collimated beam at slow axis is realized by the designed collimation lens with refraction index of 1.51.

  5. Optical coherent tomography with electrically tunable semiconductor laser using FMCW techniques

    NASA Astrophysics Data System (ADS)

    Haberland, Udo; Blazek, Vladimir; Schmitt, Hans J.

    1996-12-01

    Imaging of highly scattering objects in scattering media can play an important part in assessing melanoma in human skin. The technique to be presented is based on frequency modulated continuous waves using a coherent tunable semiconductor laser irradiating a Michelson interferometer. The electrically tunable laser is characterized and the procedure to linearize the instantaneous frequency with time is described. The temporal point spread function of dilute milk is measured. Finally the performance of our imaging system is demonstrated on 2D-images of solid scattering phantoms and of an eye of a pig.

  6. Characterization of optically pumped semiconductor lasers in pulsed mode as a function of temperature

    NASA Astrophysics Data System (ADS)

    Bai, Yanbo; Wisdom, Jeffrey; Hyland, Patrick; Scholz, Christian; Chilla, Juan

    2017-02-01

    Self-heating of Optically Pumped Semiconductor (OPS) chip has been identified as the major limiting factor of power scaling in OPS-based lasers in continuous wave (cw) mode. In this work, characterization of OPS lasers in short pulse (100 ns) and low duty cycle (1%) regime, where self-heating is negligible, as a function of the heat sink temperature is presented. This data, combined with a rigorous thermal model, allows us to predict OPS chip performance in new cooling configurations for power scaling.

  7. Imaging of free carriers in semiconductors via optical feedback in terahertz quantum cascade lasers

    SciTech Connect

    Mezzapesa, F. P. Brambilla, M.; Dabbicco, M.; Scamarcio, G.; Columbo, L. L.; Vitiello, M. S.

    2014-01-27

    To monitor the density of photo-generated charge carriers on a semiconductor surface, we demonstrate a detectorless imaging system based on the analysis of the optical feedback in terahertz quantum cascade lasers. Photo-excited free electron carriers are created in high resistivity n-type silicon wafers via low power (≅40 mW/cm{sup 2}) continuous wave pump laser in the near infrared spectral range. A spatial light modulator allows to directly reconfigure and control the photo-patterned intensity and the associated free-carrier density distribution. The experimental results are in good agreement with the numerical simulations.

  8. Nonlinear dynamics of semiconductor lasers with feedback and modulation.

    PubMed

    Toomey, J P; Kane, D M; Lee, M W; Shore, K A

    2010-08-02

    The nonlinear dynamics of two semiconductor laser systems: (i) with optical feedback, and (ii) with optical feedback and direct current modulation are evaluated from multi-GHz-bandwidth output power time-series. Animations of compilations of the RF spectrum (from the FFT of the time-series) as a function of optical feedback level, injection current and modulation signal strength is demonstrated as a new tool to give insight into the dynamics. The results are contrasted with prior art and new observations include fine structure in the RF spectrum at low levels of optical feedback and non-stationary switching between periodic and chaotic dynamics for some sets of laser system parameters. Correlation dimension analysis successfully identifies periodic dynamics but most of the dynamical states are too complex to be extracted using standard algorithms.

  9. Modeling and Simulation of Semiconductor Quantum Well Structures and Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

    1998-01-01

    In this talk I will cover two aspects of modeling and simulation efforts at NASA Ames Research Center. In the quantum well structure simulation, we typically start from the quantum mechanical calculation of the quantum well structures for the confined/and unconfined eigen states and functions. A bandstructure calculation of the k*p type is then performed for the confined valence states. This information is then used to computer the optical gain and refractive index of the quantum well structures by solving the linearized multiband semiconductor Bloch equations with the many-body interactions included. In our laser simulation, we typically solve the envelope equations for the laser field in space-time domain, coupled with a reduced set of material equations using the microscopic calculation of the first step. Finally I will show some examples of both aspects of simulation and modeling.

  10. Intracavity laser spectroscopy with a semiconductor disk laser-pumped cw Cr{sup 2+} : ZnSe laser

    SciTech Connect

    Kozlovsky, V I; Korostelin, Yu V; Podmar'kov, Yu P; Skasyrsky, Ya K; Frolov, M P; Okhotnikov, O G; Akimov, V A

    2013-09-30

    Absorption spectra of the air have been measured near 2.31 μm using intracavity laser spectroscopy with a semiconductor disk laser-pumped cw Cr{sup 2+} : ZnSe laser. It is shown that, at lasing times of at least 3 ms, the sensitivity of the laser to intracavity absorption increases. This allows one to reach an effective path length of 900 km and enables detection of weak lines with absorption coefficients down to 1 × 10{sup -9} cm{sup -1}. (laser spectroscopy)

  11. INTERNATIONAL CONFERENCE ON SEMICONDUCTOR INJECTION LASERS SELCO-87: Influence of spontaneous fluctuations on the emission spectrum of an injection semiconductor laser

    NASA Astrophysics Data System (ADS)

    Gulyaev, Yurii V.; Suris, Robert A.; Tager, A. A.; Élenkrig, B. B.

    1988-11-01

    A theoretical investigation is made of fluctuation-induced excitation of side longitudinal modes in the emission spectra of semiconductor lasers, including those with an external mirror. It is shown that nonlinear refraction of light in the active region of a semiconductor laser may result in a noise redistribution of the radiation between longitudinal resonator modes and can be responsible for the multimode nature of the average emission spectrum. An analysis is made of the influence of selectivity of an external mirror on the stability of cw operation, minimum line width, and mode composition of the emission spectra of semiconductor lasers. The conditions for maximum narrowing of the emission spectrum of a semiconductor laser with an external selective mirror are identified.

  12. MBE growth and characterization of semiconductor laser coolers

    NASA Astrophysics Data System (ADS)

    Stintz, Andreas; Li, Chia-Yeh; Sheik-Bahae, Mansoor; Malloy, Kevin J.

    2009-02-01

    Laser cooling of a semiconductor has been an elusive but highly desirable goal for several years. Although it is theoretically possible, tedious and often time-consuming sample preparation, processing and testing has slowed the progress on the experimental end. The work presented here focuses on a new approach to the first step, the growth of high quality starting samples by molecular beam epitaxy (MBE). MBE is believed to have an inherent advantage over chemical vapor deposition techniques since typically material with higher purity can be grown by MBE, thereby reducing the chance for parasitic absorption and nonradiative recombinations to occur. Additionally, with MBE very precise control over interfaces is possible, where a significant portion of the non-radiative traps are usually located. The most promising material for laser cooling is the binary compound GaAs. The lattice-matched material Ga0.515In0.485P is chosen for passivating the surface as it has shown much longer radiative lifetimes in GaAs than, for example, AlxGa1-xAs. The present study focuses on growth optimization of Ga0.515In0.485P/GaAs/Ga0.515In0.485P heterostructures and the influence of growth conditions on sample suitability for laser cooling as measured by non-radiative lifetimes in GaAs. In particular, parameters such as growth temperature, group V:III overpressure, substrate orientation, doping, and interface composition on a monolayer length scale are varied and analyzed. The suitability of an optimized sample for semiconductor laser cooling is discussed.

  13. IV-VI semiconductor lasers for gas phase biomarker detection

    NASA Astrophysics Data System (ADS)

    McCann, Patrick; Namjou, Khosrow; Roller, Chad; McMillen, Gina; Kamat, Pratyuma

    2007-09-01

    A promising absorption spectroscopy application for mid-IR lasers is exhaled breath analysis where sensitive, selective, and speedy measurement of small gas phase biomarker molecules can be used to diagnose disease and monitor therapies. Many molecules such as nitric oxide, ethane, formaldehyde, acetaldehyde, acetone, carbonyl sulfide, and carbon disulfide have been connected to diseases or conditions such as asthma, oxidative stress, breast cancer, lung cancer, diabetes, organ transplant rejection, and schizophrenia. Measuring these and other, yet to be discovered, biomarker molecules in exhaled breath with mid-IR lasers offers great potential for improving health care since such tests are non-invasive, real-time, and do not require expensive consumables or chemical reagents. Motivated by these potential benefits, mid-IR laser spectrometers equipped with presently available cryogenically-cooled IV-VI lasers mounted in compact Stirling coolers have been developed for clinical research applications. This paper will begin with a description of the development of mid-IR laser instruments and their use in the largest known exhaled breath clinical study ever performed. It will then shift to a description of recent work on the development of new IV-VI semiconductor quantum well materials and laser fabrication methods that offer the promise of low power consumption (i.e. efficient) continuous wave emission at room temperature. Taken together, the demonstration of compelling clinical applications with large market opportunities and the clear identification of a viable pathway to develop low cost mid-IR laser instrumentation can create a renewed focus for future research and development efforts within the mid-IR materials and devices area.

  14. From Dye Laser Factory to Portable Semiconductor Laser: Four Generations of Sodium Guide Star Lasers for Adaptive Optics in Astronomy and Space Situational Awareness

    NASA Astrophysics Data System (ADS)

    d'Orgeville, C.; Fetzer, G.

    This presentation recalls the history of sodium guide star laser systems used in astronomy and space situational awareness adaptive optics, analysing the impact that sodium laser technology evolution has had on routine telescope operations. While it would not be practical to describe every single sodium guide star laser system developed to date, it is possible to characterize their evolution in broad technology terms. The first generation of sodium lasers used dye laser technology to create the first sodium laser guide stars in Hawaii, California, and Spain in the late 1980's and 1990's. These experimental systems were turned into the first laser guide star facilities to equip medium-to-large diameter adaptive optics telescopes, opening a new era of LGS AO-enabled diffraction-limited imaging from the ground. Although they produced exciting scientific results, these laser guide star facilities were large, power-hungry and messy. In the USA, a second-generation of sodium lasers was developed in the 2000's that used cleaner, yet still large and complex, solid-state laser technology. These are the systems in routine operation at the 8-10m class astronomical telescopes and 4m-class satellite imaging facilities today. Meanwhile in Europe, a third generation of sodium lasers was being developed using inherently compact and efficient fiber laser technology, and resulting in the only commercially available sodium guide star laser system to date. Fiber-based sodium lasers will be deployed at two astronomical telescopes and at least one space debris tracking station this year. Although highly promising, these systems remain significantly expensive and they have yet to demonstrate high performance in the field. We are proposing to develop a fourth generation of sodium lasers: based on semiconductor technology, these lasers could provide the final solution to the problem of sodium laser guide star adaptive optics for all astronomy and space situational awareness applications.

  15. Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration

    SciTech Connect

    Loubriel, G.M.; Mar, A.; Hamil, R.A.; Zutavern, F.J.; Helgeson, W.D.

    1997-12-01

    This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered with small amounts of laser light. The specific goals of the LDRD were to demonstrate: (1) that small laser diode arrays that are potential candidates for laser-switch integration will indeed trigger the PCSS switch, and (2) that high gain GaAs switches can be used to trigger optical Q-switches in lasers such as the lasers to be used in the X-1 Advanced Radiation Source and the laser used for direct optical initiation (DOI) of explosives. The technology developed with this LDRD is now the prime candidate for triggering the Q switch in the multiple lasers in the laser trigger system of the X-1 Advanced Radiation Source and may be utilized in other accelerators. As part of the LDRD we developed a commercial supplier. To study laser/switch integration we tested triggering the high gain GaAs switches with: edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs), and transverse junction stripe (TJS) lasers. The first two types of lasers (edge emitting and VCSELs) did activate the PCSS but are harder to integrate with the PCSS for a compact package. The US lasers, while easier to integrate with the switch, did not trigger the PCSS at the US laser power levels we used. The PCSS was used to activate the Q-switch of the compact laser to be used in the X-1 Advanced Radiation Source.

  16. Pulse repetition rate scaling from 5 to 100 GHz with a high-power semiconductor disk laser.

    PubMed

    Mangold, Mario; Zaugg, Christian A; Link, Sandro M; Golling, Matthias; Tilma, Bauke W; Keller, Ursula

    2014-03-10

    The high-power semiconductor laser studied here is a modelocked integrated external-cavity surface emitting laser (MIXSEL), which combines the gain of vertical-external-cavity surface-emitting lasers (VECSELs) with the saturable absorber of a semiconductor saturable absorber mirror (SESAM) in a single semiconductor layer stack. The MIXSEL concept allows for stable and self-starting fundamental passive modelocking in a simple straight cavity and the average power scaling is based on the semiconductor disk laser concept. Previously record-high average output power from an optically pumped MIXSEL was demonstrated, however the long pulse duration of 17 ps prevented higher pulse repetition rates and many interesting applications such as supercontinuum generation and broadband frequency comb generation. With a novel MIXSEL structure, the first femtosecond operation was then demonstrated just recently. Here we show that such a MIXSEL can also support pulse repetition rate scaling from ≈5 GHz to >100 GHz with excellent beam quality and high average output power, by mechanically changing the cavity length of the linear straight cavity and the output coupler. Up to a pulse repetition rate of 15 GHz we obtained average output power >1 W and pulse durations <4 ps. Furthermore we have been able to demonstrate the highest pulse repetition rate from any fundamentally modelocked semiconductor disk laser with 101.2 GHz at an average output power of 127 mW and a pulse duration of 570 fs.

  17. Period-control and chaos-anti-control of a semiconductor laser using the twisted fiber

    NASA Astrophysics Data System (ADS)

    Yan, Sen-Lin

    2016-09-01

    A novel semiconductor laser system is presented based on a twisted fiber. To study the period-control and chaos-anti-control of the laser system, we design a type of optic path as a control setup using the combination of the twisted fiber and the polarization controller while we present a physical dynamics model of the delayed dual-feedback laser containing the twisted fiber effect. We give an analysis of the effect of the twisted fiber on the laser. We use the effects of the delayed phase and the rotation angle of the twisted fiber and the characteristics of the system to achieve control of the laser. The laser is deduced to a stable state, a double-periodic state, a period-6 state, a period-8 state, a period-9 state, a multi-period state, beat phenomenon, and so on. The periodic laser can be anti-controlled to chaos. Some chaos-anti-control area is found. The laser system is very useful for the study of chaos-control of the laser setup and the applications of some physics effects.

  18. Intermediate high index layer for laser mode tuning in organic semiconductor lasers.

    PubMed

    Stroisch, M; Woggon, T; Teiwes-Morin, C; Klinkhammer, S; Forberich, K; Gombert, A; Gerken, M; Lemmer, U

    2010-03-15

    We modified the optical properties of organic semiconductor distributed feedback lasers by introducing a high refractive index layer consisting of tantalum pentoxide between the substrate and the active material layer. A thin film of tris-(8-hydroxyquinoline) aluminium doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran was used as the active layer. By varying the intermediate layer thickness we could change the effective refractive index of the guided laser mode and thus the laser wavelength. With this technique we were able to tune the laser emission range between 613 nm and 667 nm. For high index layer thicknesses higher than 40 nm the laser operated on the TE(1)-mode rather than the fundamental TE(0)-mode.

  19. All-electronic line width reduction in a semiconductor diode laser using a crystalline microresonator

    NASA Astrophysics Data System (ADS)

    Rury, Aaron S.; Mansour, Kamjou; Yu, Nan

    2015-07-01

    This study examines the capability to significantly suppress the frequency noise of a semiconductor distributed feedback diode laser using a universally applicable approach: a combination of a high-Q crystalline whispering gallery mode microresonator reference and the Pound-Drever-Hall locking scheme using an all-electronic servo loop. An out-of-loop delayed self-heterodyne measurement system demonstrates the ability of this approach to reduce a test laser's absolute line width by nearly a factor of 100. In addition, in-loop characterization of the laser stabilized using this method demonstrates a 1-kHz residual line width with reference to the resonator frequency. Based on these results, we propose that utilization of an all-electronic loop combined with the use of the wide transparency window of crystalline materials enable this approach to be readily applicable to diode lasers emitting in other regions of the electromagnetic spectrum, especially in the UV and mid-IR.

  20. Determination of nanovibration amplitudes using frequency-modulated semiconductor laser autodyne

    SciTech Connect

    Usanov, D A; Skripal, A V; Astakhov, E I

    2014-02-28

    The method for measuring nanovibration amplitudes using the autodyne signal of a semiconductor laser at several laser radiation wavelengths is described. The theoretical description of the frequency-modulated autodyne signal under harmonic vibrations of the reflector is presented and the relations for its spectral components are derived using the expansions into the Fourier and Bessel series. The results of numerical modelling based on the proposed method for measuring the reflector nanovibration amplitudes are presented that make use of the low-frequency spectrum of the autodyne signal from the frequency-modulated laser autodyne and the solution of the appropriate inverse problem. The experimental setup is described; the results of the measurements are presented for the nanovibration amplitudes and the autodyne signal spectra under the reflector nanovibrations. (laser applications and other topics in quantum electronics)

  1. Processing and packaging of semiconductor lasers and optoelectronic devices; Proceedings of the Meeting, Los Angeles, CA, Jan. 20, 21, 1993

    NASA Astrophysics Data System (ADS)

    Temkin, Henryk

    1993-06-01

    Various papers on processing and packaging of semiconductor laser and optoelectronic devices are presented. Individual topics addressed include: buried heterostructure lasers based on InGaAsP/InP, fabrication processes for GaAs-based high-power diode lasers, fast and reliable processing of high-performance InGaAs 0.98 micron laser diodes, 1.3 micron InGaAsP/InP buried-crescent lasers with narrow spread of threshold currents, Si-based laser subassembly for telecommunications, inexpensive packaging techniques of fiber pigtailed laser diodes, high-performance packaging of gigabit data communication optical modules, applications of diamond made by chemical-vapor deposition for semiconductor laser submounts. Also discussed are: packaging of optical interconnect arrays for optical signal processing and computing, coupling 4 W cw from a diode-pumped Nd:YAG laser through a 5-micron-core single-mode fiber, microoptic and microelectronic infrared packaging of vertical-cavity laser arrays, vertical-cavity surface-emitting laser technology, direct contact-type image sensor unit.

  2. Recent developments in monolithic phase-locked semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 Watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

  3. Recent developments in monolithic phase-locked semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

  4. Optical Biosensors Based on Semiconductor Nanostructures

    PubMed Central

    Martín-Palma, Raúl J.; Manso, Miguel; Torres-Costa, Vicente

    2009-01-01

    The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented. PMID:22346691

  5. Effective observation of treatment of chronic pharyngitis with semiconductor laser irradiation at acupuncture points

    NASA Astrophysics Data System (ADS)

    Li, Suxian; Wang, Xiaoyan; Wang, Yanrong

    1993-03-01

    The treatment of this disease with laser such as He-Ne laser, Nd:YAG laser, and CO2 laser, etc., has been applied in our country, but application of the semiconductor laser therapy has received few reports. It has many advantages, such as ting volume, steady function, simple operation (the patient can operate it by himself), no side effects, remarkable results, and it is very convenient. So the semiconductor laser can be used to treat the chronic pharyngitis with irradiation on acupunctural points. One-hundred-twenty chronic pharyngitis patients were divided into 2 groups, a laser group and a medicine group, 60 cases for each. The effective rate is 91.6% and 66.6%, respectively. Obviously the treatment of chronic pharyngitis with semiconductor laser is valuable for widespread use. The principle of the laser therapy is discussed in the last part of this paper.

  6. Gigahertz self-referenceable frequency comb from a semiconductor disk laser.

    PubMed

    Zaugg, Christian A; Klenner, Alexander; Mangold, Mario; Mayer, Aline S; Link, Sandro M; Emaury, Florian; Golling, Matthias; Gini, Emilio; Saraceno, Clara J; Tilma, Bauke W; Keller, Ursula

    2014-06-30

    We present a 1.75-GHz self-referenceable frequency comb from a vertical external-cavity surface-emitting laser (VECSEL) passively modelocked with a semiconductor saturable absorber mirror (SESAM). The VECSEL delivers 231-fs pulses with an average power of 100 mW and is optimized for stable and reliable operation. The optical spectrum was centered around 1038 nm and nearly transform-limited with a full width half maximum (FWHM) bandwidth of 5.5 nm. The pulses were first amplified to an average power of 5.5 W using a backward-pumped Yb-doped double-clad large mode area (LMA) fiber and then compressed to 85 fs with 2.2 W of average power with a passive LMA fiber and transmission gratings. Subsequently, we launched the pulses into a highly nonlinear photonic crystal fiber (PCF) and generated a coherent octave-spanning supercontinuum (SC). We then detected the carrier-envelope offset (CEO) frequency (f(CEO)) beat note using a standard f-to-2f-interferometer. The f(CEO) exhibits a signal-to-noise ratio of 17 dB in a 100-kHz resolution bandwidth and a FWHM of ≈10 MHz. To our knowledge, this is the first report on the detection of the f(CEO) from a semiconductor laser, opening the door to fully stabilized compact frequency combs based on modelocked semiconductor disk lasers.

  7. Development of optically pumped DBR-free semiconductor disk lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

    2017-03-01

    Semiconductor disk lasers (SDLs) are attractive for applications requiring good beam quality, wavelength versatility, and high output powers. Typical SDLs utilize the active mirror geometry, where a semiconductor DBR is integrated with the active region by growth or post-growth bonding. This imposes restrictions for the SDL design, like material system choice, thermal management, and effective gain bandwidth. In DBR-free geometry, these restrictions can be alleviated. An integrated gain model predicts DBR-free geometry with twice the gain bandwidth of typical SDLs, which has been experimentally verified with active regions near 1 μm and 1.15 μm. The lift-off and bonding technique enables the integration of semiconductor active regions with arbitrary high quality substrates, allowing novel monolithic geometries. Bonding an active region onto a straight side of a commercial fused silica right angle prism, and attaching a high reflectivity mirror onto the hypotenuse side, with quasi CW pumping at 780 nm, lasing operation was achieved at 1037 nm with 0.2 mW average power at 1.6 mW average pump power. Laser dynamics show that thermal lens generation in the active region bottlenecks the laser efficiency. Investigations on total internal reflection based monolithic ring cavities are ongoing. These geometries would allow the intracavity integration of 2D materials or other passive absorbers, which could be relevant for stable mode locking. Unlike typical monolithic microchip SDLs, with the evanescent wave coupling technique, these monolithic geometries allow variable coupling efficiency.

  8. Transient gain analysis of gain-switched semiconductor lasers during pulse lasing.

    PubMed

    Chen, Shaoqiang; Ito, Takashi; Asahara, Akifumi; Nakamae, Hidekazu; Nakamura, Takahiro; Yoshita, Masahiro; Kim, Changsu; Zhang, Baoping; Yokoyama, Hiroyuki; Suemoto, Tohru; Akiyama, Hidefumi

    2015-12-10

    We analyzed the transient gain properties of three gain-switched semiconductor lasers with different materials and cavity structures during pulse lasing. All the semiconductor lasers were pumped with impulse optical pumping, and all the generated gain-switched output pulses were well described by exponential functions in their rise parts, wherein the transient gains were derived according to the rate-equation theoretical model. In spite of the different laser structures and materials, the results consistently demonstrated that a higher transient gain produces shorter output pulses, indicating the dominant role of higher transient gain in the generation of even shorter gain-switched pulses with semiconductor lasers.

  9. Numerical simulation of a novel all-optical flip-flop based on a chirped nonlinear distributed feedback semiconductor laser structure using GPGPU computing

    NASA Astrophysics Data System (ADS)

    Zoweil, H.

    2015-05-01

    A novel all-optical flip-flop based on a chirped nonlinear distributed feedback laser structure is proposed. The flip-flop does not require a holding beam. The optical gain is provided by a current injection into an active layer. The nonlinear wave-guiding layer consists of a chirped phase shifted grating accompanied with a negative nonlinear refractive index coefficient that increases in magnitude along the wave-guide. In the 'OFF' state, the chirped grating does not provide the required optical feedback to start lasing. An optical pulse switches the device 'ON' by reducing the chirp due to the negative nonlinear refractive index coefficient. The reduced chirp grating provides enough feedback to sustain a laser mode. The device is switched 'OFF' by cross gain modulation. GPGPU computing allows for long simulation time of multiple SET-RESET operations. The 'ON/OFF' transitions delays are in nanoseconds time scale.

  10. Optically induced transport through semiconductor-based molecular electronics

    SciTech Connect

    Li, Guangqi; Seideman, Tamar; Fainberg, Boris D.

    2015-04-21

    A tight binding model is used to investigate photoinduced tunneling current through a molecular bridge coupled to two semiconductor electrodes. A quantum master equation is developed within a non-Markovian theory based on second-order perturbation theory with respect to the molecule-semiconductor electrode coupling. The spectral functions are generated using a one dimensional alternating bond model, and the coupling between the molecule and the electrodes is expressed through a corresponding correlation function. Since the molecular bridge orbitals are inside the bandgap between the conduction and valence bands, charge carrier tunneling is inhibited in the dark. Subject to the dipole interaction with the laser field, virtual molecular states are generated via the absorption and emission of photons, and new tunneling channels open. Interesting phenomena arising from memory are noted. Such a phenomenon could serve as a switch.

  11. Optically induced transport through semiconductor-based molecular electronics

    NASA Astrophysics Data System (ADS)

    Li, Guangqi; Fainberg, Boris D.; Seideman, Tamar

    2015-04-01

    A tight binding model is used to investigate photoinduced tunneling current through a molecular bridge coupled to two semiconductor electrodes. A quantum master equation is developed within a non-Markovian theory based on second-order perturbation theory with respect to the molecule-semiconductor electrode coupling. The spectral functions are generated using a one dimensional alternating bond model, and the coupling between the molecule and the electrodes is expressed through a corresponding correlation function. Since the molecular bridge orbitals are inside the bandgap between the conduction and valence bands, charge carrier tunneling is inhibited in the dark. Subject to the dipole interaction with the laser field, virtual molecular states are generated via the absorption and emission of photons, and new tunneling channels open. Interesting phenomena arising from memory are noted. Such a phenomenon could serve as a switch.

  12. Semiconductor Laser Line-width Measurements for Space Interferometry Applications

    NASA Technical Reports Server (NTRS)

    Dougherty, D.; Guttierrez, R.; Dubovitsky, S.; Forouhar, S.

    1999-01-01

    This work discusses results using the self-heterodyne delay atechnique to measure 1.3 um InP based DFB lasers. We will also address practical issues concerning detection and elimination of back reflections, choice of fiber length and resolution, and measurement of laser 1/f and current supply noise.

  13. Advanced excimer laser technologies enable green semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Fukuda, Hitomi; Yoo, Youngsun; Minegishi, Yuji; Hisanaga, Naoto; Enami, Tatsuo

    2014-03-01

    "Green" has fast become an important and pervasive topic throughout many industries worldwide. Many companies, especially in the manufacturing industries, have taken steps to integrate green initiatives into their high-level corporate strategies. Governments have also been active in implementing various initiatives designed to increase corporate responsibility and accountability towards environmental issues. In the semiconductor manufacturing industry, there are growing concerns over future environmental impact as enormous fabs expand and new generation of equipments become larger and more powerful. To address these concerns, Gigaphoton has implemented various green initiatives for many years under the EcoPhoton™ program. The objective of this program is to drive innovations in technology and services that enable manufacturers to significantly reduce both the financial and environmental "green cost" of laser operations in high-volume manufacturing environment (HVM) - primarily focusing on electricity, gas and heat management costs. One example of such innovation is Gigaphoton's Injection-Lock system, which reduces electricity and gas utilization costs of the laser by up to 50%. Furthermore, to support the industry's transition from 300mm to the next generation 450mm wafers, technologies are being developed to create lasers that offer double the output power from 60W to 120W, but reducing electricity and gas consumption by another 50%. This means that the efficiency of lasers can be improve by up to 4 times in 450mm wafer production environments. Other future innovations include the introduction of totally Heliumfree Excimer lasers that utilize Nitrogen gas as its replacement for optical module purging. This paper discusses these and other innovations by Gigaphoton to enable green manufacturing.

  14. Power-scalable 1.57 microm mode-locked semiconductor disk laser using wafer fusion.

    PubMed

    Saarinen, Esa J; Puustinen, Janne; Sirbu, Alexei; Mereuta, Alexandru; Caliman, Andrei; Kapon, Eli; Okhotnikov, Oleg G

    2009-10-15

    We report the first (to our knowledge) wafer-fused high-power passively mode-locked semiconductor disk laser operating at 1.57 microm wavelength. An InP-based active medium was fused with GaAs/AlGaAs distributed Bragg reflector on a 2 inch wafer level, resulting in an integrated monolithic gain mirror. An intracavity wedged diamond heat-spreader capillary bonded to the gain chip provides efficient heat removal from the gain structure without disturbing the spectrum of the mode-locked laser. The laser produces over 0.6 W of average output power at 15 degrees C with 16 ps pulse width. The total output power accounting for all output beams emerging from the cavity was 0.86 W. The results reveal an essential advantage of wafer fusion processing of disparate materials over monolithically grown InP-based gain structures and demonstrate the high potential of this technique for power scaling of long-wavelength semiconductor disk lasers.

  15. Squeezed photon-number noise and sub-Poissonian electrical partition noise in a semiconductor laser

    NASA Technical Reports Server (NTRS)

    Richardson, W. H.; Machida, S.; Yamamoto, Y.

    1991-01-01

    Amplitude noise on the light from a semiconductor laser produced a photocurrent fluctuation spectrum that was a maximum of 85 percent (-8.3 dB) below the shot-noise limit. Squeezing in semiconductor lasers is not limited by the overall quantum, or current transfer, efficiency from the laser injection current to the detector photocurrent. Current leakage away from the lasing junction does not introduce Poissonian partition noise.

  16. 1.56 µm 1 watt single frequency semiconductor disk laser.

    PubMed

    Rantamäki, Antti; Rautiainen, Jussi; Sirbu, Alexei; Mereuta, Alexandru; Kapon, Eli; Okhotnikov, Oleg G

    2013-01-28

    A single frequency wafer-fused semiconductor disk laser at 1.56 µm with 1 watt of output power and a coherence length over 5 km in fiber is demonstrated. The result represents the highest output power reported for a narrow-line semiconductor disk laser operating at this spectral range. The study shows the promising potential of the wafer fusion technique for power scaling of single frequency vertical-cavity lasers emitting in the 1.3-1.6 µm range.

  17. High power semiconductor laser source for space applications

    NASA Astrophysics Data System (ADS)

    Goodwin, A. R.; Whiteaway, J. E. A.; Collar, A. J.

    1986-07-01

    Semiconductor laser sources for optical communication links between geostationary and low Earth orbiting satellites were investigated. Phase locked arrays of coupled stripes or related devices offer single mode operation at much lower optical and current density than other techniques. The highest powers are expected using GaAlAs, the best reliability using InGaAsP. Use of very thin highly doped p-InP buffer layers in planar growth, wide mesas, long cavities, and facet coating for DCPBH lasers are suggested. Continuous output power values up to 340 mW can be generated by unoptimized multimode InGaAsP lasers emitting at 1.3 microns. It should be possible to generate continuous power levels greater than 1000 mW by optimizing facet reflectivity and thermal impedance. The Y-coupled array is the most promising concept. The addition of flared output guides, and the positioning of the couplers close to the facet with the larger number of emitters, should improve performance.

  18. Multiclustered chimeras in large semiconductor laser arrays with nonlocal interactions

    NASA Astrophysics Data System (ADS)

    Shena, J.; Hizanidis, J.; Hövel, P.; Tsironis, G. P.

    2017-09-01

    The dynamics of a large array of coupled semiconductor lasers is studied numerically for a nonlocal coupling scheme. Our focus is on chimera states, a self-organized spatiotemporal pattern of coexisting coherence and incoherence. In laser systems, such states have been previously found for global and nearest-neighbor coupling, mainly in small networks. The technological advantage of large arrays has motivated us to study a system of 200 nonlocally coupled lasers with respect to the emerging collective dynamics. Moreover, the nonlocal nature of the coupling allows us to obtain robust chimera states with multiple (in)coherent domains. The crucial parameters are the coupling strength, the coupling phase and the range of the nonlocal interaction. We find that multiclustered chimera states exist in a wide region of the parameter space and we provide quantitative characterization for the obtained spatiotemporal patterns. By proposing two different experimental setups for the realization of the nonlocal coupling scheme, we are confident that our results can be confirmed in the laboratory.

  19. Semiconductor laser asymmetry cutting glass with laser induced thermal-crack propagation

    NASA Astrophysics Data System (ADS)

    Zhao, Chunyang; Zhang, Hongzhi; Wang, Yang

    2014-12-01

    Laser induced thermal-crack propagation (LITP) makes the material to produce an uneven temperature field, maximum temperature can't soften or melt the material, induces the thermal stress, then the crack separates along the cutting path. One of the problems in laser asymmetry cutting glass with LITP is the cutting deviation along scanning trajectory. This study lays great emphasis on considering the dynamic extension of crack to explain the reason of the cutting deviation in laser asymmetry cutting glass, includes asymmetric linear cutting and a quarter of a circular curve cutting. This paper indicates the experiments of semiconductor laser asymmetry cutting glass with LITP. Optical microscope photographs of the glass sheet are obtained to examine the cutting deviation. The extended finite element method (XFEM) is used to simulate the dynamic propagation of crack; the crack path does not have to be specified a priori. The cutting deviation mechanism and the crack propagation process are studied by the stress fields using finite element software ABAQUS. This work provides a theoretical basis to investigate the cutting deviation in laser asymmetry cutting glass. In semiconductor laser asymmetry cutting glass, the tensile stress is the basis of crack propagation, then the compressive stress not only makes the crack to extend stably, but also controls the direction of crack propagation.

  20. Photoconductive Semiconductor Switch Technology for Short Pulse Electromagnetics and Lasers

    SciTech Connect

    Denison, Gary J.; Helgeson, Wesley D.; Hjalmarson, Harold P.; Loubriel, Guillermo M.; Mar, Alan; O'Malley, Martin W.; Zutavern, Fred J.

    1999-08-05

    High gain photoconductive semiconductor switches (PCSS) are being used to produce high power electromagnetic pulses foc (1) compact, repetitive accelerators, (2) ultra-wide band impulse sources, (3) precision gas switch triggers, (4) optically-activated firesets, and (5) high power optical pulse generation and control. High power, sub-nanosecond optical pulses are used for active optical sensors such as compact optical radars and range-gated hallistic imaging systems. Following a brief introduction to high gain PCSS and its general applications, this paper will focus on PCSS for optical pulse generation and control. PCSS technology can be employed in three distinct approaches to optical pulse generation and control: (1) short pulse carrier injection to induce gain-switching in semiconductor lasers, (2) electro-optical Q-switching, and (3) optically activated Q-switching. The most significant PCSS issues for these applications are switch rise time, jitter, and longevity. This paper will describe both the requirements of these applications and the most recent results from PCSS technology. Experiments to understand and expand the limitations of high gain PCSS will also be described.

  1. Significant increase in wavelength, power, and temperature operating envelopes for semiconductor laser diode bars for solid-state lasers

    NASA Astrophysics Data System (ADS)

    Haden, J.; Plano, B.; Major, J.; Harnagel, G.; Endriz, J.

    Attention is given to the substantial increase in the performance envelope of AlGaAs base semiconductor laser diode array bars (QCW bars) that are available to designers of diode pumped solid-state lasers. Reliable QCW bar performance includes operation to 100 W/cm with greater than 10 exp 9 pulse life, 65 C operation, and 780 to 980 nm wavelength availability (60 W/cm). Consideration is also given to 247-W QCW operation. At Nd:YAG, YLF wavelengths (798-807 nm), significant improvements have been achieved in allowable operating temperature (to 65 C) and operating power (to 100 W). These improvements offer the opportunity for the design of high-efficiency solid-state laser systems that need to operate in relatively severe environments.

  2. Purcell effect in sub-wavelength semiconductor lasers.

    PubMed

    Gu, Qing; Slutsky, Boris; Vallini, Felipe; Smalley, Joseph S T; Nezhad, Maziar P; Frateschi, Newton C; Fainman, Yeshaiahu

    2013-07-01

    We present a formal treatment of the modification of spontaneous emission rate by a cavity (Purcell effect) in sub-wavelength semiconductor lasers. To explicitly express the assumptions upon which our formalism builds, we summarize the results of non-relativistic quantum electrodynamics (QED) and the emitter-field-reservoir model in the quantum theory of damping. Within this model, the emitter-field interaction is modified to the extent that the field mode is modified by its environment. We show that the Purcell factor expressions frequently encountered in the literature are recovered only in the hypothetical condition when the gain medium is replaced by a transparent medium. Further, we argue that to accurately evaluate the Purcell effect, both the passive cavity boundary and the collective effect of all emitters must be included as part of the mode environment.

  3. Solitary and coupled semiconductor ring lasers as optical spiking neurons.

    PubMed

    Coomans, W; Gelens, L; Beri, S; Danckaert, J; Van der Sande, G

    2011-09-01

    We theoretically investigate the possibility of generating pulses in an excitable (asymmetric) semiconductor ring laser (SRL) using optical trigger pulses. We show that the phase difference between the injected field and the electric field inside the SRL determines the direction of the perturbation in phase space. Due to the folded shape of the excitability threshold, this has an important influence on the ability to cross it. A mechanism for exciting multiple consecutive pulses using a single trigger pulse (i.e., multipulse excitability) is revealed. We furthermore investigate the possibility of using asymmetric SRLs in a coupled configuration, which is a first step toward an all-optical neural network using SRLs as building blocks.

  4. Solitary and coupled semiconductor ring lasers as optical spiking neurons

    NASA Astrophysics Data System (ADS)

    Coomans, W.; Gelens, L.; Beri, S.; Danckaert, J.; van der Sande, G.

    2011-09-01

    We theoretically investigate the possibility of generating pulses in an excitable (asymmetric) semiconductor ring laser (SRL) using optical trigger pulses. We show that the phase difference between the injected field and the electric field inside the SRL determines the direction of the perturbation in phase space. Due to the folded shape of the excitability threshold, this has an important influence on the ability to cross it. A mechanism for exciting multiple consecutive pulses using a single trigger pulse (i.e., multipulse excitability) is revealed. We furthermore investigate the possibility of using asymmetric SRLs in a coupled configuration, which is a first step toward an all-optical neural network using SRLs as building blocks.

  5. Improved low-power semiconductor diode lasers for photodynamic therapy in veterinary medicine

    NASA Astrophysics Data System (ADS)

    Lee, Susanne M.; Mueller, Eduard K.; Van de Workeen, Brian C.; Mueller, Otward M.

    2001-05-01

    Cryogenically cooling semiconductor diode lasers provides higher power output, longer device lifetime, and greater monochromaticity. While these effects are well known, such improvements have not been quantified, and thus cryogenically operated semiconductor lasers have not been utilized in photodynamic therapy (PDT). We report quantification of these results from laser power meter and photospectrometer data. The emission wavelengths of these low power multiple quantum well semiconductor lasers were found to decrease and become more monochromatic with decreasing temperature. Significant power output improvements also were obtained at cryogenic temperatures. In addition, the threshold current, i.e. the current at which lasing begins, decreased with decreasing temperature. This lower threshold current combined with the increased power output produced dramatically higher device efficiencies. It is proposed that cryogenic operation of semiconductor diode lasers will reduce the number of devices needed to produce the requisite output for many veterinary and medical applications, permitting significant cost reductions.

  6. Fundamental Limit of 1/f Frequency Noise in Semiconductor Lasers Due to Mechanical Thermal Noise

    NASA Technical Reports Server (NTRS)

    Numata, K.; Camp, J.

    2011-01-01

    So-called 1/f noise has power spectral density inversely proportional to frequency, and is observed in many physical processes. Single longitudinal-mode semiconductor lasers, used in variety of interferometric sensing applications, as well as coherent communications, exhibit 1/f frequency noise at low frequency (typically below 100kHz). Here we evaluate mechanical thermal noise due to mechanical dissipation in semiconductor laser components and give a plausible explanation for the widely-observed 1/f frequency noise, applying a methodology developed for fixed-spacer cavities for laser frequency stabilization. Semiconductor-laser's short cavity, small beam radius, and lossy components are expected to emphasize thermal-noise-limited frequency noise. Our simple model largely explains the different 1/f noise levels observed in various semiconductor lasers, and provides a framework where the noise may be reduced with proper design.

  7. Spatial and Spectral Brightness Enhancement of High Power Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Leidner, Jordan Palmer

    The performance of high-power broad-area diode lasers is inhibited by beam filamentation induced by free-carrier-based self-focusing. The resulting beam degradation limits their usage in high-brightness, high-power applications such as pumping fiber lasers, and laser cutting, welding, or marking. Finite-difference propagation method simulations via RSoft's BeamPROP commercial simulation suite and a custom-built MATLAB code were used for the study and design of laser cavities that suppress or avoid filamentation. BeamPROP was used to design a tapered, passive, multi-mode interference cavity for the creation of a self-phase-locking laser array, which is comprised of many single-mode gain elements coupled to a wide output coupler to avoid damage from local high optical intensities. MATLAB simulations were used to study the effects of longitudinal and lateral cavity confinement on lateral beam quality in conventional broad-area lasers. This simulation was expanded to design a laser with lateral gain and index prescription that is predicted to operate at or above state-of-the-art powers while being efficiently coupled to conventional telecom single-mode optical fibers. Experimentally, a commercial broad-area laser was coupled in the far-field to a single-mode fiber Bragg grating to provide grating-stabilized single-mode laser feedback resulting in measured spectral narrowing for efficient pump absorption. Additionally a 19 GHz-span, spatially resolved, self-heterodyne measurement was made of a broad-area laser to study the evolution/devolution of the mode content of the emitted laser beam with increasing power levels.

  8. Flexible optical clock recovery utilizing a multi-function semiconductor fiber laser

    NASA Astrophysics Data System (ADS)

    Feng, H.; Zhao, W.; Xie, X. P.; Qian, F. C.; Wang, W.; Huang, X.; Hu, H.

    2013-08-01

    We demonstrate a multi-function fiber laser based on cross-gain modulation in a semiconductor optical amplifier (SOA). Depending on the input signals, the fiber cavity can emit a continuous wave (CW) laser, mode-locked pulses, or act as a clock recovery device. With an extra CW light overcoming the pattern effect in the clock recovery process, a 10-GHz synchronous clock sequence with <0.1 power fluctuation and <120-fs timing jitter is extracted from the transmission return-to-zero data stream. We further analyze the recovered clock properties as a function of the input signal, and find that the clock recovery system presents good stability over a large range of input signal characteristics. The multi-function fiber laser exhibits the advantages of compact configuration and low cost, which is very convenient and attractive for optical communications and signal processing.

  9. Optimizing electrically pumped vertical extended cavity surface emitting semiconductor lasers (E-VECSELs)

    NASA Astrophysics Data System (ADS)

    McInerney, John G.; Mooradian, Aram

    2011-03-01

    The future evolution of photonics, for a wide spectrum of applications ranging from established optical telecommunications to emerging opportunities such as biotechnology, reprographics and projection displays, will depend on availability of compact, rugged, efficient and inexpensive lasers which deliver high power, good beam quality, excellent wavelength stability, low noise and long lifetime in the near infrared and visible regions. This combination is not readily available from either of the traditional classes of semiconductor laser, edge-emitters and vertical cavity surface emitters (VCSELs). Here we describe a novel class of laser based on geometry similar to VCSELs but controlled by an extended coupled cavity. These devices are scalable to high powers while maintaining fundamental spatial mode performance, a feature that is essential to efficient coupling into a single mode optical fibre or waveguide, or long range propagation in free space. They are also ideally suited to mode locking, gain-switching and intracavity frequency conversion, among other applications.

  10. Apparatus For Linewidth Reduction in Distributed Feedback or Distributed Bragg Reflector Semiconductor Lasers Using Vertical Emission

    NASA Technical Reports Server (NTRS)

    Cook, Anthony L. (Inventor); Hendricks, Herbert D. (Inventor)

    2000-01-01

    The linewidth of a distributed feedback semiconductor laser or a distributed Bragg reflector laser having one or more second order gratings is reduced by using an external cavity to couple the vertical emission back into the laser. This method and device prevent disturbance of the main laser beam, provide unobstructed access to laser emission for the formation of the external cavity, and do not require a very narrow heat sink. Any distributed Bragg reflector semiconductor laser or distributed feedback semiconductor laser that can produce a vertical emission through the epitaxial material and through a window in the top metallization can be used. The external cavity can be formed with an optical fiber or with a lens and a mirror or grating.

  11. III-V Semiconductor Quantum Well Lasers and Related Optoelectronic Devices on Silicon (Abstracts)

    DTIC Science & Technology

    1990-06-01

    REPORT DATE 3. R E PO R T T Y P E A N D DATES COVERED TITLE AND SUBTITLE S. FUNDING NUMBERS N III-V Semiconductor Quantum Well Lasers and Related T...continued on reverse side) 14. SUtJECT TERMS 15. NUMBER OF PAGES Semiconductor Conductor Quantum Well Lasers, Optoelectronic Devices, Silicon...Further work, which is to appear later, is listed as Refs. 11-15. I * * II | | *, | I .. . . 3 III-V SEMICONDUCTOR QUANTUM WELL LASERS AND RELATED

  12. Quantum dot semiconductor disk laser at 1.3  μm.

    PubMed

    Rantamäki, Antti; Sokolovskii, Grigorii S; Blokhin, Sergey A; Dudelev, Vladislav V; Soboleva, Ksenia K; Bobrov, Mikhail A; Kuzmenkov, Alexander G; Vasil'ev, Alexey P; Gladyshev, Andrey G; Maleev, Nikolai A; Ustinov, Victor M; Okhotnikov, Oleg

    2015-07-15

    We present a semiconductor disk laser (SDL) emitting at the wavelength of 1.3 μm. The active region of the SDL comprises InAs quantum dots (QDs) that are embedded into InGaAs quantum wells (QWs). An output power over 200 mW is obtained at 15°C, which represents the highest output power reported from QD-based SDLs in this wavelength range. The results demonstrate the feasibility of QD-based gain media for fabricating SDLs emitting at 1.3 μm.

  13. Tunable narrow linewidth AlGaInP semiconductor disk laser for Sr atom cooling applications.

    PubMed

    Pabœuf, David; Hastie, Jennifer E

    2016-07-01

    We report a frequency-stabilized semiconductor disk laser based on AlGaInP and operating at 689 nm, a wavelength of interest for atomic clocks based on strontium atoms. With a gain structure designed for emission at around 690 nm, more than 100 mW of output power are generated in single-frequency operation. We show that the source can be tuned over 8 nm with pm precision. By servo-locking the frequency to the side of fringe of a reference cavity, we demonstrate rms frequency noise of 5.2 kHz.

  14. 1 W at 785 nm from a frequency-doubled wafer-fused semiconductor disk laser.

    PubMed

    Rantamäki, Antti; Rautiainen, Jussi; Lyytikäinen, Jari; Sirbu, Alexei; Mereuta, Alexandru; Kapon, Eli; Okhotnikov, Oleg G

    2012-04-09

    We demonstrate an optically pumped semiconductor disk laser operating at 1580 nm with 4.6 W of output power, which represents the highest output power reported from this type of laser. 1 W of output power at 785 nm with nearly diffraction-limited beam has been achieved from this laser through intracavity frequency doubling, which offers an attractive alternative to Ti:sapphire lasers and laser diodes in a number of applications, e.g., in spectroscopy, atomic cooling and biophotonics.

  15. Modeling and cavity optimization of an external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Feies, Valentin I.; Montrosset, Ivo

    2004-09-01

    Semiconductor external cavity lasers (ECL) have a wide range of applications in the field of DWDM and measurement systems. One of their most important features is the continuous tuning without mode hopping in a wide wavelength range. In this paper we present a modelling approach for an ECL in Littman-Metcalf configuration carried out for optimising: 1) the laser diode position inside the cavity in order to maximize the range of continuous wavelength tuning without mode hopping and without cavity-length adjustment and 2) the choice of the detuning of the operating wavelength respect to the Bragg condition in order to minimize the four-wave mixing (FWM) effects and the effect of a non-perfect antireflection coating (ARC). A realistic example has been analyzed and therefore we considered: the wavelength dependence of the modal gain, linewidth enhancement factor and grating selectivity, as well as the modal refractive index change with carrier injection, operating wavelength and temperature. The implemented numerical tools allow also to obtain some specifications on the grating selectivity and the ARC design.

  16. Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers.

    PubMed

    Xu, Yanqing; Chen, Qi; Zhang, Chunfeng; Wang, Rui; Wu, Hua; Zhang, Xiaoyu; Xing, Guichuan; Yu, William W; Wang, Xiaoyong; Zhang, Yu; Xiao, Min

    2016-03-23

    Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 10(6) GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm(-1)) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.

  17. Content-Based Image Retrieval for Semiconductor Process Characterization

    NASA Astrophysics Data System (ADS)

    Tobin, Kenneth W.; Karnowski, Thomas P.; Arrowood, Lloyd F.; Ferrell, Regina K.; Goddard, James S.; Lakhani, Fred

    2002-12-01

    Image data management in the semiconductor manufacturing environment is becoming more problematic as the size of silicon wafers continues to increase, while the dimension of critical features continues to shrink. Fabricators rely on a growing host of image-generating inspection tools to monitor complex device manufacturing processes. These inspection tools include optical and laser scattering microscopy, confocal microscopy, scanning electron microscopy, and atomic force microscopy. The number of images that are being generated are on the order of 20,000 to 30,000 each week in some fabrication facilities today. Manufacturers currently maintain on the order of 500,000 images in their data management systems for extended periods of time. Gleaning the historical value from these large image repositories for yield improvement is difficult to accomplish using the standard database methods currently associated with these data sets (e.g., performing queries based on time and date, lot numbers, wafer identification numbers, etc.). Researchers at the Oak Ridge National Laboratory have developed and tested a content-based image retrieval technology that is specific to manufacturing environments. In this paper, we describe the feature representation of semiconductor defect images along with methods of indexing and retrieval, and results from initial field-testing in the semiconductor manufacturing environment.

  18. Study of the effects of semiconductor laser irradiation on peripheral nerve injury

    NASA Astrophysics Data System (ADS)

    Xiong, G. X.; Li, P.

    2012-11-01

    In order to study to what extent diode laser irradiation effects peripheral nerve injury, the experimental research was made on rabbits. Experimental results show that low-energy semiconductor laser can promote axonal regeneration and improve nervous function. It is also found that simultaneous exposure of the injured peripheral nerve and corresponding spinal segments to laser irradiation may achieve the most significant results.

  19. Ultrafast switching based on field optical bistability in nano-film of semiconductor

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Egorenkov, Vladimir A.; Loginova, Maria M.

    2016-09-01

    Using computer simulation, we show a possibility of ultrafast switching between stable states of an optical bistable device based on nano-film of semiconductor. Optical bistability occurs because of nonlinear dependence of semiconductor absorption coefficient on electric field potential. Electric field is induced by a laser pulse due to charged particles generation. The main feature of this bistable element is low absorption energy, which is necessary for switching, in comparison with bistable element based on other physical mechanism of laser energy absorption. For computer simulation of a problem under consideration a new finite-difference scheme is proposed using the original iterative process.

  20. Excimer laser induced diffusion in magnetic semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Howari, H.; Sands, D.; Nicholls, J. E.; Hogg, J. H. C.; Stirner, T.; Hagston, W. E.

    2000-08-01

    Studies of pulsed laser annealing (PLA) of CdTe/CdMnTe quantum well structures are made in order to examine depth dependent effects in laser irradiated semiconductors. Since diffusion coefficients are strongly dependent on the temperature, depth resolution is achieved because the diffusion of Mn from the barriers into the quantum wells is depth dependent. Multiple quantum well (MQW) structures of CdTe/CdMnTe were annealed with single pulses from an XeCl laser at 308 nm. At a threshold of 90 mJ cm-2 two new emission bands are observed that are attributed to the diffusion of Mn from barrier layers to QWs. The diffusion associated with these bands, measured as the integrated product of the diffusion constant and time, is found to be 300 and 30 Å2. Calculations of the temperature, reached within the surface following PLA, using an analytical solution of the heat diffusion equation coupled with known high temperature diffusion coefficients predict the diffusion to decrease by one order of magnitude within one period at the top of the MQW stack. It is suggested that at the threshold surface melting occurs and that these emission bands arise from the QWs immediately beneath the melt front. The diffusion of Mn ions into the QWs is confirmed by magneto-optical data. A further emission band occurs at this same threshold with a Mn concentration above that of the concentration in the barrier layers of the MQW stack. This emission is attributed tentatively to the segregation of the Mn ion within the molten region following recrystallization.

  1. Compact ultrafast semiconductor disk laser for nonlinear imaging in living organisms

    NASA Astrophysics Data System (ADS)

    Aviles-Espinosa, Rodrigo; Filippidis, G.; Hamilton, Craig; Malcolm, Graeme; Weingarten, Kurt J.; Südmeyer, Thomas; Barbarin, Yohan; Keller, Ursula; Artigas, David; Loza-Alvarez, Pablo

    2011-03-01

    Ultrashort pulsed laser systems (such as Ti:sapphire) have been used in nonlinear microscopy during the last years. However, its implementation is not straight forward as they are maintenance-intensive, bulky and expensive. These limitations have prevented their wide-spread use for nonlinear imaging, especially in "real-life" biomedical applications. In this work we present the suitability of a compact ultrafast semiconductor disk laser source, with a footprint of 140x240x70 mm, to be used for nonlinear microscopy. The modelocking mechanism of the laser is based on a quantumdot semiconductor saturable absorber mirror (SESAM). The laser delivers an average output power of 287 mW with 1.5 ps pulses at 500 MHz, corresponding to a peak power of 0.4 kW. Its center wavelength is 965 nm which is ideally suited for two-photon excitation of the widely used Green Fluorescent Protein (GFP) marker as it virtually matches its twophoton action cross section. We reveal that it is possible to obtain two photon excited fluorescence images of GFP labeled neurons and secondharmonic generation images of pharynx and body wall muscles in living C. elegans nematodes. Our results demonstrate that this compact laser is well suited for long-term time-lapse imaging of living samples as very low powers provide a bright signal. Importantly this non expensive, turn-key, compact laser system could be used as a platform to develop portable nonlinear bio-imaging devices, facilitating its wide-spread adoption in "real-life" applications.

  2. Merged beam laser design for reduction of gain-saturation and two-photon absorption in high power single mode semiconductor lasers.

    PubMed

    Lysevych, M; Tan, H H; Karouta, F; Fu, L; Jagadish, C

    2013-04-08

    In this paper we report a method to overcome the limitations of gain-saturation and two-photon absorption faced by developers of high power single mode InP-based lasers and semiconductor optical amplifiers (SOA) including those based on wide-waveguide or slab-coupled optical waveguide laser (SCOWL) technology. The method is based on Y-coupling design of the laser cavity. The reduction in gain-saturation and two-photon absorption in the merged beam laser structures (MBL) are obtained by reducing the intensity of electromagnetic field in the laser cavity. Standard ridge-waveguide lasers and MBLs were fabricated, tested and compared. Despite a slightly higher threshold current, the reduced gain-saturation in MBLs results in higher output power. The MBLs also produced a single spatial mode, as well as a strongly dominating single spectral mode which is the inherent feature of MBL-type cavity.

  3. Toward High Performance Integrated Semiconductor Micro and Nano Lasers Enabled by Transparent Conducting Materials: from Thick Structure to Thin Film

    NASA Astrophysics Data System (ADS)

    Ou, Fang

    Integrated semiconductor lasers working at the wavelength around 1.3 microm and 1.55 microm are of great interest for the research of photonic integrated circuit (PIC) since they are the crucial components for optical communications and many other applications. To satisfy the requirement of the next generation optical communication and computing systems, integrated semiconductor lasers are expected to have high device performance like very low lasing threshold, high output powers, high speed and possibility of being integrated with electronics. This dissertation focuses on the design and realization of InP based high performance electrically pumped integrated semiconductor lasers. In the dissertation, we first design the tall structure based electrically pumped integrated micro-lasers. Those lasers are capable of giving >10 mW output power with a moderate low threshold current density (0.5--5 kA/cm 2). Besides, a new enhanced radiation loss based coupler design is demonstrated to realize single directional output for curvilinear cavities. Second, the thin film structure based integrated semiconductor laser designs are proposed. Both structures use the side conduction geometry to enable the electrical injection into the thin film laser cavity. The performance enhancement of the thin film structure based lasers is analyzed compared to the tall structure. Third, we investigate the TCO materials. CdO deposited by PLD and In 2O3 deposited by IAD are studied from aspects of their physical, optical and electrical properties. Those materials can give a wide range of tunability in their conductivity (1--5000 S/cm) and optical transparency (loss 200--5000 cm-1), which is of great interest in realizing novel nanophotonic devices. In addition, the electrical contact properties of those materials to InP are also studied. Experiment result shows that both CdO and In2O3 can achieve good ohmic contact to n-InP with contact resistance as low as 10-6O·cm 2. At last, we investigate

  4. Synchronization of bandwidth-enhanced chaos in semiconductor lasers with optical feedback and injection.

    PubMed

    Someya, Hiroyuki; Oowada, Isao; Okumura, Haruka; Kida, Takahiko; Uchida, Atsushi

    2009-10-26

    We experimentally investigate the generation and synchronization of bandwidth-enhanced chaos in a semiconductor laser (drive laser) that is subject to optical injection from another chaotic semiconductor laser (injection laser) with optical feedback. Effective bandwidth enhancement is achieved over 12 GHz, under the condition in which the optical wavelength of the drive laser is positively detuned with respect to that of the injection laser, outside the injection locking range. The bandwidth-enhanced chaotic signal of the drive laser is injected into a third semiconductor laser (response laser) for synchronization. Synchronization of chaos with a bandwidth greater than 12 GHz is observed between the drive and response lasers, under the condition in which the optical wavelength of the response laser is negatively detuned with respect to that of the drive laser, satisfying the injection locking condition. High-quality chaos synchronization is observed within the injection locking range between the drive and response lasers and under the condition of a low relaxation oscillation frequency of the response laser.

  5. Highly efficient neodymium:yttrium aluminum garnet laser end pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Sipes, D. L.

    1985-01-01

    In recent experiments, 80-mW CW power in a single mode has been achieved from a neodymium:yttrium aluminum garnet (Nd:YAG) laser with only 1 W of electrical power input to a single semiconductor laser array pump. This corresponds to an overall efficiency of 8 percent, the highest reported CW efficiency for a Nd:YAG laser. A tightly focused semiconductor laser end pump configuration is used to achieve high pumping intensities (on the order of 1 kW/sq cm), which in turn causes the photon to photon conversion efficiency to approach the quantum efficiency (76 percent for Nd:YAG at 1.06 microns pumped at 0.810 micron). This is achieved despite the dual-lobed nature of the pump. Through the use of simple beam-combining schemes (e.g., polarization coupling and multireflection point pumping), output powers over 1 W and overall electrical to optical efficiencies as high as 10 percent are expected.

  6. High-power semiconductor lasers at eye-safe wavelengths

    NASA Astrophysics Data System (ADS)

    Osowski, Mark L.; Gewirtz, Yossi; Lammert, Robert M.; Oh, Se W.; Panja, Chameli; Elarde, Victor C.; Vaissie, Laurent; Patel, Falgun D.; Ungar, Jeffrey E.

    2009-05-01

    InP based diode lasers are required to realize the next generation of eyesafe applications, including direct rangefinding and HEL weapons systems. We report on the progress of high power eyesafe single spatial and longitudinal mode 1550nm MOPA devices, where we have achieved peak powers in excess of 10W with 50ns pulse widths. A conceptual model based on our recent MOPA results show the path towards scaling to high powers based on spatial beam combination with operating conditions suitable for direct rangefinding applications. We also report on the progress towards high power 14xx and 15xx nm pump lasers for eyesafe HEL systems.

  7. Multi-phonon-assisted absorption and emission in semiconductors and its potential for laser refrigeration

    SciTech Connect

    Khurgin, Jacob B.

    2014-06-02

    Laser cooling of semiconductors has been an elusive goal for many years, and while attempts to cool the narrow gap semiconductors such as GaAs are yet to succeed, recently, net cooling has been attained in a wider gap CdS. This raises the question of whether wider gap semiconductors with higher phonon energies and stronger electron-phonon coupling are better suitable for laser cooling. In this work, we develop a straightforward theory of phonon-assisted absorption and photoluminescence of semiconductors that involves more than one phonon and use to examine wide gap materials, such as GaN and CdS and compare them with GaAs. The results indicate that while strong electron-phonon coupling in both GaN and CdS definitely improves the prospects of laser cooling, large phonon energy in GaN may be a limitation, which makes CdS a better prospect for laser cooling.

  8. Stable, continuous-wave, intracavity, optical parametric oscillator pumped by a semiconductor disk laser (VECSEL).

    PubMed

    Stothard, D J M; Hopkins, J-M; Burns, D; Dunn, M H

    2009-06-22

    We report relaxation oscillation free, true continuous-wave operation of a singly-resonant, intracavity optical parametric oscillator (OPO) based upon periodically-poled, MgO-doped LiNbO3 and pumped internal to the cavity of a compact, optically-excited semiconductor disk laser (or VECSEL). The very short upper-laser-state lifetime of this laser gain medium, coupled with the enhancing effect of the high-finesse pump laser cavity in which the OPO is located, enables a low threshold, high efficiency intracavity device to be operated free of relaxation oscillations in continuous-wave mode. By optimizing for low-power operation, parametric threshold was achieved at a diode-laser power of only 1.4 W. At 8.5 W of diode-laser power, 205 mW of idler power was extracted, indicating a total down-converted power of 1.25 W, and hence a down-conversion efficiency of 83%.

  9. Low spatial coherence electrically pumped semiconductor laser for speckle-free full-field imaging.

    PubMed

    Redding, Brandon; Cerjan, Alexander; Huang, Xue; Lee, Minjoo Larry; Stone, A Douglas; Choma, Michael A; Cao, Hui

    2015-02-03

    The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ∼1,000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, which combines the low spatial coherence of a LED with the high spectral radiance of a laser, could enable a wide range of high-speed, full-field imaging and projection applications.

  10. Low spatial coherence electrically pumped semiconductor laser for speckle-free full-field imaging

    PubMed Central

    Redding, Brandon; Cerjan, Alexander; Huang, Xue; Lee, Minjoo Larry; Stone, A. Douglas; Choma, Michael A.; Cao, Hui

    2015-01-01

    The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ∼1,000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, which combines the low spatial coherence of a LED with the high spectral radiance of a laser, could enable a wide range of high-speed, full-field imaging and projection applications. PMID:25605946

  11. Semiconductor Laser Theory: The Maxwell--Bloch Equations

    NASA Astrophysics Data System (ADS)

    Gehrig, Edeltraud; Hess, Ortwin

    Because of its central importance for fundamental physics as well as for technological applications, the electronic structure of layered semiconductor structures has attracted much interest over the last two decades. In theoretical studies, methods based on the envelope function approximation are predominant, the reason being that the EFA allows a comprehensive description of electron- and hole-like states. It can cope with periodic or aperiodic geometries of quantum structures, as well as perturbations such as a magnetic field, strain, or a built-in or external potential. Details of the underlying crystal potential are included in terms of bulk band structure parameters.

  12. Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid (Inventor)

    1990-01-01

    An Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 micron radiation with a pump power to output power of efficiency as high as 68 percent. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77 K with an efficiency as high as 68 percent up to ambient room temperature with an efficiency at that temperature as high as 9 percent.

  13. Irradiation effect of polarization direction and intensity of semiconductor laser on injured peripheral nerve

    NASA Astrophysics Data System (ADS)

    Guo-Xin, Xiong; Lei-lei, Xiong

    2016-08-01

    To investigate the irradiation effect of polarization direction and the intensity of a semiconductor laser on the injured peripheral nerve in rabbits, the model of the injured common peroneal nerve was established, the L5,6 spinal segments of the rabbits were irradiated, a uniform rotating polarizer was placed at the laser output which made the polarization direction and intensity of the output laser change according to the 80 Hz cosine law. The experimental results show that irradiating the spinal segment of injured nerves in rabbits with this changeable semiconductor laser can significantly promote the regeneration of injured peripheral nerves and the function recovery.

  14. Emergence of resonant mode-locking via delayed feedback in quantum dot semiconductor lasers.

    PubMed

    Tykalewicz, B; Goulding, D; Hegarty, S P; Huyet, G; Erneux, T; Kelleher, B; Viktorov, E A

    2016-02-22

    With conventional semiconductor lasers undergoing external optical feedback, a chaotic output is typically observed even for moderate levels of the feedback strength. In this paper we examine single mode quantum dot lasers under strong optical feedback conditions and show that an entirely new dynamical regime is found consisting of spontaneous mode-locking via a resonance between the relaxation oscillation frequency and the external cavity repetition rate. Experimental observations are supported by detailed numerical simulations of rate equations appropriate for this laser type. The phenomenon constitutes an entirely new mode-locking mechanism in semiconductor lasers.

  15. Phase noise reduction of a semiconductor laser in a composite optical phase-locked loop

    NASA Astrophysics Data System (ADS)

    Satyan, Naresh; Sendowski, Jacob; Vasilyev, Arseny; Rakuljic, George; Yariv, Amnon

    2010-12-01

    The bandwidth and residual phase noise of optical phase-locked loops (OPLLs) using semiconductor lasers are typically constrained by the nonuniform frequency modulation response of the laser, limiting their usefulness in a number of applications. It is shown in this work that additional feedback control using an optical phase modulator improves the coherence between the master and slave lasers in the OPLL by achieving bandwidths determined only by the propagation delay in the loop. A phase noise reduction by more than a factor of two is demonstrated in a proof-of-concept experiment using a commercial distributed feedback semiconductor laser.

  16. Extracting physical properties of arbitrarily shaped laser-doped micro-scale areas in semiconductors

    SciTech Connect

    Heinrich, Martin; Kluska, Sven; Hameiri, Ziv; Hoex, Bram; Aberle, Armin G.

    2013-12-23

    We present a method that allows the extraction of relevant physical properties such as sheet resistance and dopant profile from arbitrarily shaped laser-doped micro-scale areas formed in semiconductors with a focused pulsed laser beam. The key feature of the method is to use large laser-doped areas with an identical average number of laser pulses per area (laser pulse density) as the arbitrarily shaped areas. The method is verified using sheet resistance measurements on laser-doped silicon samples. Furthermore, the method is extended to doping with continuous-wave lasers by using the average number of passes per area or density of passes.

  17. Single longitudinal mode control of semiconductor lasers by rectangular conical diffractor system for wavelength-division-multiplexing transmission

    NASA Astrophysics Data System (ADS)

    Sato, H.; Suzuki, N.; Itoh, K.; Fukai, M.

    1982-03-01

    A new external feedback system named the rectangular conical diffractor (RCD), which is composed of a diffraction grating and a mirror, is designed. This system has advantages for wavelength-division-multiplexing transmission systems. By using this system in both single and multimode semiconductor lasers: 1) the oscillation wavelength of a semiconductor laser can be selected freely; 2) some semiconductor lasers oscillate at different wavelengths from one another simultaneously, and no interference exists between the oscillation wavelengths under the condition that each semiconductor laser is operated independently; and 3) the selected wavelength is stable against temperature variation of the lasers.

  18. Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution

    SciTech Connect

    Henn, T.; Kiessling, T. Ossau, W.; Molenkamp, L. W.; Biermann, K.; Santos, P. V.

    2013-12-15

    We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast “white light” supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.

  19. Non-Shilnikov cascades of spikes and hubs in a semiconductor laser with optoelectronic feedback.

    PubMed

    Freire, Joana G; Gallas, Jason A C

    2010-09-01

    Incomplete homoclinic scenarios were recently measured in a semiconductor laser with optoelectronic feedback. We show here that such a laser contains cascades of spirals of periodic oscillations and hubs which look identical to the familiar ones observed in complete homoclinic scenarios. This means that hubs are far more general than presumed so far, being not limited by Shilnikov's theorem. Laser hubs open the possibility of measuring complex distributions of non-Shilnikov laser oscillations, and we briefly discuss how to do it.

  20. Lifetime of high-power GaAs photoconductive semiconductor switch triggered by laser of different power density

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Wang, Wei; Shen, Yi; Shi, Jinshui; Zhang, Linwen; Xia, Liansheng

    2015-02-01

    Conduction modes of GaAs photoconductive semiconductor switch (PCSS) and their conditions are expounded. Laser diode and high-power picosecond Nd:YAG lasers are used as triggers for nonlinear mode and quasi-linear mode respectively in high-power conduction experiment. GaAs PCSS`s failure mechanisms and factors influencing lifetime in both modes are analyzed. It is found that the power density of laser at trigger time determines in which mode GaAs PCSS operates. Low-power laser triggers a nonlinear mode conduction in which GaAs PCSS`s lifetime is only 103, while high-power laser triggers a quasi-linear mode conduction in which GaAs PCSS`s lifetime is up to 105. According to the findings, the compact high-power pulsed power system based on mass of GaAs PCSSs demands for miniature high-power laser generators.

  1. Incorporating many-body effects into modeling of semiconductor lasers and amplifiers

    SciTech Connect

    Ning, C.Z.; Moloney, J.V.; Indik, R.A.

    1997-06-01

    Major many-body effects that are important for semiconductor laser modeling are summarized. The authors adopt a bottom-up approach to incorporate these many-body effects into a model for semiconductor lasers and amplifiers. The optical susceptibility function ({Chi}) computed from the semiconductor Bloch equations (SBEs) is approximated by a single Lorentzian, or a superposition of a few Lorentzians in the frequency domain. Their approach leads to a set of effective Bloch equations (EBEs). The authors compare this approach with the full microscopic SBEs for the case of pulse propagation. Good agreement between the two is obtained for pulse widths longer than tens of picoseconds.

  2. Record Pulsed Power Demonstration of a 2 micron GaSb-Based Optically Pumped Semiconductor Laser Grown Lattice-Mismatched on an AlAs/GaAs Bragg Mirror and Substrate (Postprint)

    DTIC Science & Technology

    2009-09-01

    semiconductor disk lasers OPSL or, equivalently, vertical external cavity surface emitting semi- conductor lasers VECSEL , are emerging as novel sources...wavelengths in TEM00 beams. Direct genera- tion of red light at 670 nm with powers close to 0.5 W has also been demonstrated.4 These VECSEL structures...growth of InGaSb QW stacks on AlGaSb/GaSb Bragg mirrors. The latter have been employed to demonstrate 3–5 W VECSEL lasing between 2 and 2.3 m.5 Two

  3. Room-temperature 2D semiconductor activated vertical-cavity surface-emitting lasers.

    PubMed

    Shang, Jingzhi; Cong, Chunxiao; Wang, Zilong; Peimyoo, Namphung; Wu, Lishu; Zou, Chenji; Chen, Yu; Chin, Xin Yu; Wang, Jianpu; Soci, Cesare; Huang, Wei; Yu, Ting

    2017-09-14

    Two-dimensional (2D) semiconductors are opening a new platform for revitalizing widely spread optoelectronic applications. The realisation of room-temperature vertical 2D lasing from monolayer semiconductors is fundamentally interesting and highly desired for appealing on-chip laser applications such as optical interconnects and supercomputing. Here, we present room-temperature low-threshold lasing from 2D semiconductor activated vertical-cavity surface-emitting lasers (VCSELs) under continuous-wave pumping. 2D lasing is achieved from a 2D semiconductor. Structurally, dielectric oxides were used to construct the half-wavelength-thick cavity and distributed Bragg reflectors, in favour of single-mode operation and ultralow optical loss; in the cavity centre, the direct-bandgap monolayer WS2 was embedded as the gain medium, compatible with the planar VCSEL configuration and the monolithic integration technology. This work demonstrates 2D semiconductor activated VCSELs with desirable emission characteristics, which represents a major step towards practical optoelectronic applications of 2D semiconductor lasers.Two-dimensional materials have recently emerged as interesting materials for optoelectronic applications. Here, Shang et al. demonstrate two-dimensional semiconductor activated vertical-cavity surface-emitting lasers where both the gain material and the lasing characteristics are two-dimensional.

  4. Semiconductor nanocrystal-based phagokinetic tracking

    DOEpatents

    Alivisatos, A Paul; Larabell, Carolyn A; Parak, Wolfgang J; Le Gros, Mark; Boudreau, Rosanne

    2014-11-18

    Methods for determining metabolic properties of living cells through the uptake of semiconductor nanocrystals by cells. Generally the methods require a layer of neutral or hydrophilic semiconductor nanocrystals and a layer of cells seeded onto a culture surface and changes in the layer of semiconductor nanocrystals are detected. The observed changes made to the layer of semiconductor nanocrystals can be correlated to such metabolic properties as metastatic potential, cell motility or migration.

  5. Self-injected semiconductor distributed feedback lasers for frequency chirp stabilization.

    PubMed

    Kechaou, Khalil; Grillot, Frédéric; Provost, Jean-Guy; Thedrez, Bruno; Erasme, Didier

    2012-11-05

    It is well known that semiconductor distributed feedback lasers (DFB) are key devices for optical communications. However direct modulation applications are limited by the frequency chirp induced by current modulation. We demonstrate that a proper external control laser operation leads to chirp-to-power ratio (CPR) stabilization over a wide range of modulation frequencies as compared to the free-running case. Under experimentally selected optical feedback conditions, the CPR decreases significantly in the adiabatic regime from about 650 MHz/mW in the solitary case down to 65 MHz/mW. Experimental results are also confirmed by numerical investigations based on the transfer matrix method. Simulations point out the possible optimization of the CPR in the adiabatic regime by considering a judicious cavity design in conjunction with a proper external control. These results demonstrate important routes for improving the transmission performance in optical telecommunication systems.

  6. Numerical analysis of thermal effects in semiconductor disk laser with TEC cooler

    NASA Astrophysics Data System (ADS)

    Zhu, Renjiang; Zhang, Peng; Jiang, Maohua

    2016-11-01

    Based on generalized heat transfer model of thermoelectric cooler(TEC), the heat management model of semiconductor disk laser with TEC cooler has been built. With finite element method, this article has calculated the temperature distribution characteristics, and studied the effects of TEC current, heat exchange coefficient, the heatsink and the pump laser for the maximum temperature of quantum wells. Calculations show that the heat transfer coefficient significantly affects the ability of the TEC temperature shift, cooling system performance which is nearly inversely proportional to the heatsink thermal conductivity is not sensitive to its the thickness variation, and the performance of oxygen-free copper with optimization of the area is close to diamond. Meanwhile the maximum temperature of the quantum well has a linear relationship with the pump power, and increasing the pump spot size is an effective way to increase the optical power output

  7. Ultrashort pulse generation by semiconductor mode-locked lasers at 760 nm.

    PubMed

    Wang, Huolei; Kong, Liang; Forrest, Adam; Bajek, David; Haggett, Stephanie E; Wang, Xiaoling; Cui, Bifeng; Pan, Jiaoqing; Ding, Ying; Cataluna, Maria Ana

    2014-10-20

    We demonstrate the first semiconductor mode-locked lasers for ultrashort pulse generation at the 760 nm waveband. Multi-section laser diodes based on an AlGaAs multi-quantum-well structure were passively mode-locked, resulting in the generation of pulses at around 766 nm, with pulse durations down to ~4 ps, at pulse repetition rates of 19.4 GHz or 23.2 GHz (with different laser cavity lengths of 1.8 mm and 1.5 mm, respectively). The influence of the bias conditions on the mode-locking characteristics was investigated for these new lasers, revealing trends which can be ascribed to the interplay of dynamical processes in the saturable absorber and gain sections. It was also found that the front facet reflectivity played a key role in the stability of mode-locking and the occurrence of self-pulsations. These lasers hold significant promise as light sources for multi-photon biomedical imaging, as well as in other applications such as frequency conversion into the ultraviolet and radio-over-fibre communications.

  8. Compact, High Power, Multi-Spectral Mid-Infrared Semiconductor Laser Package

    DTIC Science & Technology

    2001-10-01

    Pumped (OP) type-II lasers The optically pumped laser devices were tested by pumping with 980 nm diode laser . Figure 29 shows the typical...Choi, and D. A. Coppeta "High-power diode - laser - pumped InAsSb/GaSb and GaInAsSb/GaSb lasers emitting from 3 to 4 µm" Appl. Phys. Lett. 64, 152 (1994...Arias, M. Zandian, R. R. Zucca, and Y.-Z. Liu "High-power diode - pumped mid-infrared semiconductor lasers ," Proc. SPIE 2382, 262

  9. Tunable Yb:CaF2-SrF2 laser and femtosecond mode-locked performance based on semiconductor saturable absorber mirrors.

    PubMed

    Zhang, Feng; Zhu, Hongtong; Liu, Jie; He, Yifeng; Jiang, Dapeng; Tang, Fei; Su, Liangbi

    2016-10-10

    We experimentally demonstrate an effective continuous-wave tunable operation and femtosecond passively mode-locked pulse from a Yb:CaF2-SrF2 mixed crystal laser for the first time. Pumped by a 977 nm fiber-coupled laser diode, a continuous-wave mode-locked pulse as short as 634 fs was generated. The shortest pulse operated under a repetition rate of 87 MHz at the central wavelength of 1047 nm. The calculated time-bandwidth product was 0.503, which was 1.6 times the Fourier transform-limited sech2-shaped pulses.

  10. Efficient discharge lasers pumped by double-discharge circuits with semiconductor opening switch

    NASA Astrophysics Data System (ADS)

    Panchenko, Alexei N.

    2010-11-01

    Review on application of double-discharge circuits with inductive energy storage (IES) and semiconductor opening switch (SOS) for development of efficient gas lasers is presented. It was shown that the IES allows to form long-lived stable discharge in different gas mixtures. As a result, pulse duration, output energy and efficiency of the lasers under study were improved.

  11. Intensity noise reduction in semiconductor lasers by amplitude-phase decorrelation

    NASA Technical Reports Server (NTRS)

    Vahala, Kerry J.; Newkirk, Michael A.

    1990-01-01

    Detuned operation of a laser results in coupling of field amplitude and phase fluctuations. In a semiconductor laser, this coupling is known to be very large. Here it is demonstrated that it can be used to significantly reduce intensity noise below its intrinsic limit.

  12. Parametric distortion of the optical absorption edge of a magnetic semiconductor by a strong laser field

    SciTech Connect

    Nunes, O.A.C.

    1985-09-15

    The influence of a strong laser field on the optical absorption edge of a direct-gap magnetic semiconductor is considered. It is shown that as the strong laser intensity increases the absorption coefficient is modified so as to give rise to an absorption tail below the free-field forbidden gap. An application is made for the case of the EuO.

  13. Study of the emission spectra of a 1320-nm semiconductor disk laser and its second harmonic

    SciTech Connect

    Gochelashvili, K S; Derzhavin, S I; Evdokimova, O N; Zolotovskii, I O; Podmazov, S V

    2016-03-31

    The spectral characteristics of an optically pumped external-cavity semiconductor disk laser near λ = 1320 nm are studied experimentally. Intracavity second harmonic generation is obtained using an LBO nonlinear crystal. The output power at a wavelength of 660 nm in the cw regime was 620 mW, and the peak power in the pulsed regime was 795 mW. (lasers)

  14. CONTROL OF LASER RADIATION PARAMETERS: Harmonic modulation of radiation of an external-feedback semiconductor laser

    NASA Astrophysics Data System (ADS)

    Sukharev, Aleksandr G.; Napartovich, A. P.

    2007-02-01

    The appearance of the harmonic modulation regime at the Hopf bifurcation point is described analytically for a delayed-feedback semiconductor laser. The second-order delay differential equation with complex coefficients is derived. The frequency of oscillations appearing at the Hopf bifurcation point is determined by the solution of two relatively simple transcendental equations, from which the bifurcation point itself is found. These equations contain dependences on all the control parameters of the problem. The exact upper and lower limits of the oscillation frequency are found. A comparison with numerical results shows that the modulation frequency is preserved almost constant in a broad range of feedback phases. A procedure is proposed for determining the parameters of the laser providing the presence of bifurcations with a passage to oscillations with the specified frequency. The results obtained in the paper are of interest for WDM communication systems.

  15. Cubic zirconia as a high-quality facet coating for semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Chin, A. K.; Satyanarayan, A.; Zarrabi, J. H.; Vetterling, W.

    1988-08-01

    In this paper we describe the properties of high-quality, semiconductor laser facet coatings based on yttria-stabilizied cubic zirconia (90-m% ZrO2/10-m% Y2O3). We have found that cubic zirconia films can be reproducibly deposited by electron-beam evaporation with an index of refraction of 1.98 at 6328 Å, almost ideal for use as a single-layer antireflection coating for GaAs/GaAlAs-based lasers. ZrO2 has a monoclinic crystal structure at room temperature, but changes to tetragonal, hexagonal, and cubic phases upon heating to higher temperatures. However, the addition of the Y2O3 stabilizes ZrO2 in the cubic form, thus allowing electron-beam deposition of thin films of this material to be more controllable and reproducible without the usual addition of oxygen into the vacuum chamber during deposition. Preliminary aging tests of high-power GaAs/GaAlAs lasers show that cubic zirconia films suppress the photo-enhanced oxidation of laser facets that degrades device performance.

  16. Narrow linewidth single-mode semiconductor laser development for coherent detection lidar

    NASA Technical Reports Server (NTRS)

    Mansour, Kamjou; Ksendzov, Alexander; Menzies, Robert T.; Maker, Paul D.; Muller, Richard E.; Manfra, M. J.; Turner, George W.

    2003-01-01

    High power, tunable, single mode, narrow linewidth semiconductor lasers in the 2.05-(micro)m wavelength region are needed to develop semiconductor laser reference oscillators for optical remote sensing from Earth orbit. 2.05-I1/4m narrow linewidth monolithic distributed feedback (DFB) and distributed Bragg reflector (DBR) with the external grating ridge waveguide lasers fabricated from epitaxially grown InGaAs/InGaAsP/InP and in InGaAsSb/AlGaAsSb/GaSb heterostructures are reported.

  17. Narrow linewidth single-mode semiconductor laser development for coherent detection lidar

    NASA Technical Reports Server (NTRS)

    Mansour, Kamjou; Ksendzov, Alexander; Menzies, Robert T.; Maker, Paul D.; Muller, Richard E.; Manfra, M. J.; Turner, George W.

    2003-01-01

    High power, tunable, single mode, narrow linewidth semiconductor lasers in the 2.05-(micro)m wavelength region are needed to develop semiconductor laser reference oscillators for optical remote sensing from Earth orbit. 2.05-I1/4m narrow linewidth monolithic distributed feedback (DFB) and distributed Bragg reflector (DBR) with the external grating ridge waveguide lasers fabricated from epitaxially grown InGaAs/InGaAsP/InP and in InGaAsSb/AlGaAsSb/GaSb heterostructures are reported.

  18. Rate-equation model for multi-mode semiconductor lasers with spatial hole burning.

    PubMed

    Lenstra, Daan; Yousefi, Mirvais

    2014-04-07

    We present a set of rate equations for the modal amplitudes and carrier-inversion moments that describe the deterministic multi-mode dynamics of a semiconductor laser due to spatial hole burning. Mutual interactions among the lasing modes, induced by high- frequency modulations of the carrier distribution, are included by carrier-inversion moments for which rate equations are given as well. We derive the Bogatov effect of asymmetric gain suppression in semiconductor lasers and illustrate the potential of the model for a two and three-mode laser by numerical and analytical methods.

  19. Modeling of relative intensity noise and terminal electrical noise of semiconductor lasers using artificial neural network

    NASA Astrophysics Data System (ADS)

    Rezaei, A.; Noori, L.

    2016-06-01

    In this paper, artificial neural network (ANN) is used to predict the source laser's relative intensity noise (RIN) and the terminal electrical noise (TEN) of semiconductor lasers. For this purpose, the multi-layer perceptron (MLP) neural network trained with the back propagation algorithm is used. To develop this model, the normalized bias current and frequency are selected as the input parameters and the RIN and TEN of semiconductor lasers are selected as the output parameters. The obtained results show that the proposed ANN model is in a good agreement with the numerical method, and a small error between the predicted values and the numerical solution is obtained. Therefore, the proposed ANN model is a useful, reliable, fast and cheap tool to predict the RIN and TEN of semiconductor lasers.

  20. A study on the optical parts for a semiconductor laser module

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Girl; Lee, Dong-Kil; Kim, Yang-Gyu; Lee, Kwang-Hoon; Park, Young-Sik; Jang, Kwang-Ho; Kang, Seung-Goo

    2014-11-01

    A semiconductor laser module consists of a LD (laser diode) chip that generates a laser beam, two cylindrical lenses to collimate the laser beam, a high-reflection mirror to produce a large output by collecting the laser beam, a collimator lens to guide the laser beam to an optical fiber and a protection filter to block reflected laser light that might damage the LD chip. The cylindrical lenses used in a semiconductor laser module are defined as FACs (fast axis collimators) and SACs (slow axis collimators) and are attached to the system module to control the shape of the laser beam. The FAC lens and the SAC lens are made of a glass material to protect the lenses from thermal deformation. In addition, they have aspheric shapes to improve optical performances. This paper presents a mold core grinding process for an asymmetrical aspheric lens and a GMP (glass molding press), what can be used to make aspheric cylindrical lenses for use as FACs or SACs, and a protection filter made by using IAD (ion-beam-assisted deposition). Finally, we developed the aspheric cylindrical lenses and the protection filter for a 10-W semiconductor laser module.

  1. Room-temperature-operation visible-emission semiconductor diode lasers

    NASA Technical Reports Server (NTRS)

    Ladany, I.; Kressel, H.; Nuese, C. J.

    1977-01-01

    There were two main approaches taken to develop shorter wavelength lasers. (1) Based on (AlGa)As and liquid-phase epitaxy, significant new results were obtained: Properties of these laser diodes (power output, spectra, and beam patterns), materials considerations, laser theory, and growth problems are discussed. The design of (AlGa)As layers is discussed from the vertical point of view, and various design curves are given. Horizontal structural requirements are also discussed. Experimental results from measurements done as a function of hydrostatic pressure are correlated with other results. (2) The first heterojunction laser structures using GaAs sub l-x P sub x and In sub y Ga sub l-y P at compositions, where the lattice constants are matched, were grown using vapor-phase growth technology and are described in detail, including experimental device results. Threshold current densities from 3,000 to 5,000 A per sq cm. and emission wavelengths from 6,520 A to 6,640 A were obtained at 77 K. The limiting factor in these devices is nonradiative recombination at the heterojunctions. Life tests on facet-coated (AlGa)As CW diodes are reported.

  2. A Hydrodynamic Theory for Spatially Inhomogeneous Semiconductor Lasers: Microscopic Approach

    NASA Technical Reports Server (NTRS)

    Li, Jianzhong; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)

    2001-01-01

    Starting from the microscopic semiconductor Bloch equations (SBEs) including the Boltzmann transport terms in the distribution function equations for electrons and holes, we derived a closed set of diffusion equations for carrier densities and temperatures with self-consistent coupling to Maxwell's equation and to an effective optical polarization equation. The coherent many-body effects are included within the screened Hartree-Fock approximation, while scatterings are treated within the second Born approximation including both the in- and out-scatterings. Microscopic expressions for electron-hole (e-h) and carrier-LO (c-LO) phonon scatterings are directly used to derive the momentum and energy relaxation rates. These rates expressed as functions of temperatures and densities lead to microscopic expressions for self- and mutual-diffusion coefficients in the coupled density-temperature diffusion equations. Approximations for reducing the general two-component description of the electron-hole plasma (EHP) to a single-component one are discussed. In particular, we show that a special single-component reduction is possible when e-h scattering dominates over c-LO phonon scattering. The ambipolar diffusion approximation is also discussed and we show that the ambipolar diffusion coefficients are independent of e-h scattering, even though the diffusion coefficients of individual components depend sensitively on the e-h scattering rates. Our discussions lead to new perspectives into the roles played in the single-component reduction by the electron-hole correlation in momentum space induced by scatterings and the electron-hole correlation in real space via internal static electrical field. Finally, the theory is completed by coupling the diffusion equations to the lattice temperature equation and to the effective optical polarization which in turn couples to the laser field.

  3. Ionization balance in semiconductor quantum-dot lasers

    NASA Astrophysics Data System (ADS)

    Pan, Janet L.

    1994-01-01

    The commonly assumed quasiequilibrium particle distribution with the same quasi-Fermi-level for all quantum-dot carriers in the same energy (conduction or valence) band is found not to be valid for a wide range of temperatures at the inversion populations and bound energy separations (greater than a LO phonon energy) used in the literature. Bound state occupation factors obtained from the steady state solution of rate equations describing the ionization balance in room-temperature 100-Å-radius GaAs quantum dots whose centers are separated by 400 Å are found to be very different from the quasiequilibrium distribution used in an example from the literature. In such quantum dots, bound state transitions result from collisions between charged particles via the Coulomb interaction, and from interband and intraband radiative processes. The critical free electron concentration above which collisional processes can establish a quasiequilibrium in the conduction band is found to exceed 1019 cm-3. Our numerical solution is in good agreement with Pitaevskii's model from atomic physics of an electron random walk in energy as modeled by a Fokker-Planck equation. In our simple model, electrons are captured into a bound conduction band state via three-body recombination and phonon emission, and drop into lower energy bound states via a series of collisional deexcitations before combining with a valence band hole. Solution of the rate equations is standard in numerical studies of stimulated emission in atomic plasmas, but our present discussion is, to our knowledge, the first in the literature on semiconductor quantum-dot lasers.

  4. IV-VI semiconductor growth on silicon substrates and new mid-infrared laser fabrication methods

    PubMed

    McCann; Chao; Sachar; McAlister; Li; Fang; Wu; Namjou

    1999-09-01

    This paper reviews results from research conducted at the University of Oklahoma on the development of new IV-VI semiconductor (lead salt) epitaxial growth and laser fabrication procedures that can ultimately lead to dramatic increases in mid-IR laser operating temperatures. Work has focused on growth of IV-VI semiconductor laser structures on silicon substrates using buffer layers that contain BaF2. Recent experiments show that it is possible to obtain high crystalline quality IV-VI semiconductor layer structures on (111)-oriented silicon substrates using molecular beam epitaxy (MBE) or on (100)-oriented silicon using a combination of MBE and liquid phase epitaxy (LPE). Experimental data for IV-VI semiconductor layer structures grown on silicon substrates including crystalline quality information as determined by high resolution X-ray diffraction (HRXRD) measurements and absorption edge information as determined by Fourier transform infrared (FTIR) transmission measurements are presented. Results show that these materials can be used to fabricate lasers that cover the 3 microns (3333 cm-1) to 16 microns (625 cm-1) spectral range. Removal of IV-VI semiconductor laser structures from the silicon growth substrate by dissolving BaF2 buffer layers with water is also demonstrated. This allows epitaxially-grown laser structures to be sandwiched between two heat sinks with a minimum of thermally resistive IV-VI semiconductor material. Theoretical modeling predicts that IV-VI lasers fabricated this way will have maximum continuous wave (cw) operating temperatures at least 60 degrees higher than those of IV-VI lasers fabricated on PbSe or PbTe substrates.

  5. III-V Semiconductor Quantum Well Lasers and Related Optoelectronic Devices on Silicon

    DTIC Science & Technology

    1989-12-01

    GaIxAs-GaAs Quantum Well Heterostructure Laser Structures Grown by MOCVD on TI MBE GaAs-on-Si "Substrates." Crystal Growth Buffer Layers Photopumped...Research Triangle Park, NC 27709-2211 ELEMENT NO. NO. NO. ACCESSIN NO. 11. TITLE (include Security Oas filcation) III-V Semiconductor Quantum Well ...further develop quantum well heterostructure (QWH) lasers and to realize reliable Al Ga, As-GaAs QWH lasers on Si. In spite of the significant lattice

  6. III-V Semiconductor Quantum Well Lasers and Related Optoelectronic Devices (On Silicon)

    DTIC Science & Technology

    1992-06-01

    heterostructure (QWH) lasers. Silicon IILD is used to intermix the quantum well and waveguide regions with the surrounding confining layers (beyond the laser...SUBTITLE S. FUNDING NUMBERS III-V Semiconductor Quantum Well Lasers and Related Optoelectronic Devices (On Silicon) DAAL03-89-K-0008 6 AUTHOR(S) N. Holonyak...Maximum 200 words) Since the beginning of this project (10+ years ago) we have been concerned with quantum well heterostructures (QWHs) and their use in

  7. Two-photon fluorescence bioimaging with an all-semiconductor laser picosecond pulse source.

    PubMed

    Kuramoto, Masaru; Kitajima, Nobuyoshi; Guo, Hengchang; Furushima, Yuji; Ikeda, Masao; Yokoyama, Hiroyuki

    2007-09-15

    We have demonstrated successful two-photon excitation fluorescence bioimaging using a high-power pulsed all-semiconductor laser. Toward this purpose, we developed a pulsed light source consisting of a mode-locked laser diode and a two-stage diode laser amplifier. This pulsed light source provided optical pulses of 5 ps duration and having a maximum peak power of over 100 W at a wavelength of 800 nm and a repetition frequency of 500 MHz.

  8. Nanoimprinted organic semiconductor laser pumped by a light-emitting diode.

    PubMed

    Tsiminis, Georgios; Wang, Yue; Kanibolotsky, Alexander L; Inigo, Anto R; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A

    2013-05-28

    An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs.

  9. Generation of high-power ultrashort optical pulses by semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Dudelev, V. V.; Zazulin, S. V.; Kolykhalova, E. D.; Losev, S. N.; Deryagin, A. G.; Kuchinskii, V. I.; Efanov, M. V.; Sokolovskii, G. S.

    2016-12-01

    Fiber-coupled semiconductor lasers have been studied when pumped by high-power short electrical pulses of 5 ns width and leading front duration below 1 ns. In this pumping regime, it is possible to ensure significant sharpening of output pulses, the duration of which decreases below 80 ps for a single-mode laser and below 120 ps for a broad aperture multimode laser at an output peak optical power as high as 1.5 and 27 W, respectively.

  10. Theory of active mode locking of a semiconductor laser in an external cavity

    NASA Technical Reports Server (NTRS)

    Yeung, J. A.

    1981-01-01

    An analytical treatment is given for the active mode locking of a semiconductor laser in an external resonator. The width of the mode-locked pulses is obtained as a function of the laser and cavity parameters and the amount of frequency detuning. The effects of self-modulation and saturation are included in the treatment. The pulse output is compared with that obtained by a strong modulation of the laser diode with no external cavity.

  11. Semiconductor laser with a birefringent external cavity for information systems with wavelength division multiplexing

    SciTech Connect

    Paranin, V D; Matyunin, S A; Tukmakov, K N

    2013-10-31

    The spectrum of a semiconductor laser with a birefringent external Gires – Tournois cavity is studied. The generation of two main laser modes corresponding to the ordinary and extraordinary wave resonances is found. It is shown that the radiation spectrum is controlled with a high energy efficiency without losses for spectral filtration. The possibility of using two-mode lasing in optical communication systems with wavelength division multiplexing is shown. (control of laser radiation parameters)

  12. High power single-frequency continuously-tunable compact extended-cavity semiconductor laser.

    PubMed

    Laurain, A; Myara, M; Beaudoin, G; Sagnes, I; Garnache, A

    2009-06-08

    We demonstrate high power high efficiency (0:3 W) low noise single frequency operation of a compact extended-cavity surface-emitting-semiconductor-laser exhibiting a continuous tunability over 0:84 THz with high beam quality. We took advantage of thermal lens-based stability to develop a short (< 3 mm) plano-plano external cavity without any intracavity filter. The structure is optically pumped by a 1 W commercial 830 nm multimode diode laser. No heat management was required. We measured a low divergence circular TEM(00) beam at the diffraction limit (M(2) < 1:05) with a linear light polarization (> 37 dB). The side mode suppression ratio is 60 dB. The free running laser linewidth is 850 kHz limited by pump induced thermal fluctuations. Thanks to this high-Q external cavity approach, the frequency noise is low and the dynamics is in the relaxation-oscillation-free regime, exhibiting a low intensity noise, with a cutoff frequency approximately 250 MHz above which the shot noise level is reached. We show that pump properties define the cavity design and laser coherence.

  13. New semiconductor diode laser emitting at 2 um for microsurgery applications

    NASA Astrophysics Data System (ADS)

    Gobbi, Pier Giorgio; Ragazzi, D.; Azzolini, Claudio; Trabucchi, Giuseppe; Brancato, Rosario

    1996-01-01

    A surgical laser instrument is presented, based on a semiconductor diode emitting in the spectral region around 2 micrometer, in continuous mode. At this wavelength tissue absorption is via histological water, and the interaction is purely thermal. A portable laser station was built, emitting up to 250 mW of optical power at 1.94 micrometers, out of the tip of a low- hydroxil fused-silica optical fiber of 200 micrometer diameter. Experiments have been performed both in vitro with enucleated porcine eyes and in vivo, on rabbits and rats. In vitreo-retinal surgery, retinectomies and incisions of epiretinal fibrotic membranes have been achieved. At reduced output power the laser radiation has been applied to the welding of tissues, in particular cornea, sclera and skin, with interesting results. This new laser source, characterized by ergonomic advantages like compactness, portability, long lifetime, reduced maintenance, is potentially attractive for a number of microsurgical procedures like micro- incisions, shallow coagulations, and welding of hydrated biological membranes.

  14. Reaction-diffusion optoelectronics based on dispersed semiconductors

    NASA Astrophysics Data System (ADS)

    Gradov, O. V.; Gradova, M. A.

    2015-11-01

    Since many dispersed semiconductors are capable of light energy conversion and possess photocatalytic and luminescent properties, and any discreet light-sensitive medium can be applied for the positional-sensitive light flux registration (similar to pixels and voxels in semiconductor-based image recording), the use of chemically active dispersed semiconductors allows to perform a direct signal / image registration based on light-sensitive reaction-diffusion redox systems without conventional CCD / CMOS devices. The image capturing in this case will correspond to the formation of the metastable dissipative structures in the active medium, with their morphological properties determined by the flux gradient and provided by the corresponding dispersed semiconductor medium sensitivity.

  15. Fabrication and characterization of spherical micro semiconductor crystals by laser ablation method

    NASA Astrophysics Data System (ADS)

    Shimogaki, Tetsuya; Okazaki, Kota; Yamasaki, Kota; Fusazaki, Koshi; Mizokami, Yasuaki; Tetsuyama, Norihiro; Higashihata, Mitsuhiro; Ikenoue, Hiroshi; Nakamura, Daisuke; Okada, Tatsuo

    2014-10-01

    We have been establishing the technique of fabricating spherical semiconductor microcrystals with suitable diameters for whispering gallery mode (WGM) lasing. Concretely, semiconductor microspheres were synthesized by ablating various semiconductor-sintered targets with focused pulsed laser at high fluences. In this report, dependences of fabricated zinc oxide (ZnO) microstructures on laser wavelengths were investigated. Lasing characteristics and photoluminescence of ZnO microspheres were determined, and photoluminescence of Sb-doped ZnO microspheres were determined. Additionally, it was also found that Sb-doped ZnO and aluminum nitride microspheres can be similarly synthesized. By developing this method, which does not require complex processing, it is expected that efforts in the application of WGM lasing are accelerated in many kinds of semiconductors.

  16. Relative refractory period in an excitable semiconductor laser.

    PubMed

    Selmi, F; Braive, R; Beaudoin, G; Sagnes, I; Kuszelewicz, R; Barbay, S

    2014-05-09

    We report on experimental evidence of neuronlike excitable behavior in a micropillar laser with saturable absorber. We show that under a single pulsed perturbation the system exhibits subnanosecond response pulses and analyze the role of the laser bias pumping. Under a double pulsed excitation we study the absolute and relative refractory periods, similarly to what can be found in neural excitability, and interpret the results in terms of a dynamical inhibition mediated by the carrier dynamics. These measurements shed light on the analogy between optical and biological neurons and pave the way to fast spike-time coding based optical systems with a speed several orders of magnitude faster than their biological or electronic counterparts.

  17. Selective mode coupling in microring resonators for single mode semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Arbabi, Amir

    Single mode semiconductor laser diodes have many applications in optical communications, metrology and sensing. Edge-emitting single mode lasers commonly use distributed feedback structures, or narrowband reflectors such as distributed Bragg reflectors (DBRs) and sampled grating distributed Bragg reflectors (SGDBRs). Compact, narrowband reflectors with high reflectivities are of interest to replace the commonly used DBRs and SGDBRs. This thesis presents our work on the simulation, design, fabrication, and characterization of devices operating based on the coupling of degenerate modes of a microring resonator, and investigation of the possibility of using them for improving the performance of laser diodes. In particular, we demonstrate a new type of compact, narrowband, on-chip reflector realized by selectively coupling degenerate modes of a microring resonator. For the simulation and design of reflective microring resonators, a fast and accurate analysis method is required. Conventional numerical methods for solving Maxwell's equations such as the finite difference time domain and the finite element method (FEM) provide accurate results but are computationally intense and are not suitable for the design of large 3D structures. We formulated a set of coupled mode equations that, combined with 2D FEM simulations, can provide a fast and accurate tool for the modeling and design of reflective microrings. We developed fabrication processing recipes and fabricated passive reflective microrings on silicon substrates with a silicon nitride core and silicon dioxide cladding. Narrowband single wavelength reflectors were realized which are 70 times smaller than a conventional DBR with the same bandwidth. Compared to the conventional DBR, they have faster roll-off, and no side modes. The smaller footprint saves real estate, reduces tuning power and makes these devices attractive as in-line mirrors for low threshold narrow linewidth laser diodes. Self-heating caused by material

  18. Plasma Heating and Ultrafast Semiconductor Laser Modulation Through a Terahertz Heating Field

    NASA Technical Reports Server (NTRS)

    Li, Jian-Zhong; Ning, C. Z.

    2000-01-01

    Electron-hole plasma heating and ultrafast modulation in a semiconductor laser under a terahertz electrical field are investigated using a set of hydrodynamic equations derived from the semiconductor Bloch equations. The self-consistent treatment of lasing and heating processes leads to the prediction of a strong saturation and degradation of modulation depth even at moderate terahertz field intensity. This saturation places a severe limit to bandwidth achievable with such scheme in ultrafast modulation. Strategies for increasing modulation depth are discussed.

  19. Generation of terahertz radiation by a surface ballistic photocurrent in semiconductors under subpicosecond laser excitation

    SciTech Connect

    Ziaziulia, P. A.; Malevich, V. L.; Manak, I. S.; Krotkus, A.

    2012-02-15

    An analytical model describing the onset of a surface ballistic photocurrent in cubic semiconductors under femtosecond laser excitation is proposed. It is shown that the contribution of the photocurrent component parallel to the surface to the generation of terahertz pulses may be comparable to the contribution of the perpendicular component. Consideration of the cubic symmetry of a semiconductor leads to the azimuthal anisotropy of terahertz generation.

  20. Above 2-μm emitting GaSb-based semiconductor disk laser with <100-kHz linewidth at 1000-mW output power

    NASA Astrophysics Data System (ADS)

    Kaspar, Sebastian; Rattunde, Marcel; Töpper, Tino; Rösener, Benno; Manz, Christian; Köhler, Klaus; Wagner, Joachim

    2012-03-01

    In this paper we report on the development of narrow-linewidth vertical-external-cavity surface-emitting laser (VECSEL) at a wavelength of >2 μm. Starting from a laboratory setup, we designed a highly stable VECSEL module machined from a solid block of aluminum. For linewidth precise measurements, heterodyne beatnote measurements were employed. For this firstgeneration module a linewidth of 9 kHz was achieved when actively stabilizing the laser wavelength, whereas without stabilization the linewidth amounted to 45 kHz at an output power of 100 mW, both data referring to a 100-μs sampling time. To further increase the output power, a second-generation module was fabricated, for which the on-chip mode diameter was increased. This allowed operation at a larger pump-spot diameter and still maintaining TEM00 operation, while increasing the maximum pump power and hence the output power. This module yielded an output power above 1 W in single-mode operation at a linewidth of 60 kHz (100 μs sampling time) without active wavelength stabilization. Modehop-free single-mode operation could be maintained for more than 18 hours. This new multiple-Watt, narrow-linewidth VECSEL module is apt for plane-to-ground communications without the necessity of amplifiers.

  1. Electrically pumped spaser based on semiconductor film / graphene / dielectric structure

    NASA Astrophysics Data System (ADS)

    Dadoenkova, Yuliya S.; Moiseev, Sergey G.; Zolotovskii, Igor O.; Pavlov, Dmitrii A.

    2017-09-01

    We propose a model of slow surface plasmon polariton distributed feedback laser (spaser) with pump by drift currents in graphene. This model is a kind of hybrid of a distributed feedback laser and a well-known in microwave technology travelling-wave tube. The amplification of SPP wave is created by drift currents in the graphene, and the feedback is realized due to a periodic change of the semiconductor film thickness.

  2. Demonstration of arbitrary channel selection utilizing a pulse-injected semiconductor laser with a phase-locked loop.

    PubMed

    Juan, Yu-Shan; Lin, Fan-Yi

    2011-01-17

    An arbitrary channel selection system based on a pulse-injected semiconductor laser with a phase-locked loop (PLL) is experimentally demonstrated and characterized. Through optical injection from a tunable laser, channels formed by the frequency components of a microwave frequency comb generated in the pulse-injected semiconductor laser are individually selected and enhanced. Selections of a primary channel at the fundamental frequency of 1.2 GHz and a secondary channel in a range from 10.8 to 18 GHz are shown, where the selection is done by adjusting the injection strength from the tunable laser. Suppression ratios of 44.5 and 25.9 dB between the selected primary and secondary channels to the averaged magnitude of the unwanted channels are obtained, respectively. To show the spectral quality of the pulse-injected laser, a single sideband (SSB) phase noise of -60 dBc/kHz at an offset frequency of 25 kHz is measured. Moreover, the conversion gain between the primary and secondary channels and the crosstalk between the selected channels to the adjacent unwanted channels are also investigated. Without the need of expensive external modulators, arbitrary channel selection is realized in the proposed system where the channel spacing and selection can be continuously adjusted through tuning the controllable laser parameters.

  3. Tunable high-power blue external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Lv, Xueqin; Chen, Xinyi; Wang, Fei; Zhang, Jiangyong; Che, Kaijun

    2017-09-01

    A commercially available high-power GaN-based blue laser diode has been operated in a simple Littrow-type external cavity (EC). Two kinds of EC configurations with the grating lines perpendicular (A configuration) and parallel (B configuration) to the p-n junction are evaluated. Good performance has been demonstrated for the EC laser with B configuration due to the better mode selection effect induced by the narrow feedback wavelength range from the grating. Under an injection current of 1100 mA, the spectral linewidth is narrowed significantly down to ∼0.1 nm from ∼1 nm (the free-running width), with a good wavelength-locking behavior and a higher than 35 dB-amplified spontaneous emission suppression ratio. Moreover, a tuning bandwidth of 3.6 nm from 443.9 nm to 447.5 nm is realized with output power of 1.24 W and EC coupling efficiency of 80% at the central wavelength. The grating-coupled blue EC laser with narrow spectral linewidth, flexible wavelength tunability, and high output power shows potential applications in atom cooling and trapping, high-resolution spectroscopy, second harmonic generation, and high-capacity holographic data storage.

  4. High-power optically pumped semiconductor laser apllications

    NASA Astrophysics Data System (ADS)

    Morioka, S. Brandon

    2011-03-01

    OPS lasers have found applications in various industrial and scientific laser applications due to their power scaling capability, their wide range of emission wavelengths, physical size and their superior reliability. This paper provides an overview of commercially available OPS lasers and the applications in which they are used including biotechnology, medical, holography, Titanium-Sapphire laser pumping, non-lethal defense, forensics, and entertainment.

  5. Quantifying stochasticity in the dynamics of delay-coupled semiconductor lasers via forbidden patterns.

    PubMed

    Tiana-Alsina, Jordi; Buldú, Javier M; Torrent, M C; García-Ojalvo, Jordi

    2010-01-28

    We quantify the level of stochasticity in the dynamics of two mutually coupled semiconductor lasers. Specifically, we concentrate on a regime in which the lasers synchronize their dynamics with a non-zero lag time, and the leader and laggard roles alternate irregularly between the lasers. We analyse this switching dynamics in terms of the number of forbidden patterns of the alternate time series. The results reveal that the system operates in a stochastic regime, with the level of stochasticity decreasing as the lasers are pumped further away from their lasing threshold. This behaviour is similar to that exhibited by a single semiconductor laser subject to external optical feedback, as its dynamics shifts from the regime of low-frequency fluctuations to coherence collapse. This journal is © 2010 The Royal Society

  6. Thermally robust semiconductor optical amplifiers and laser diodes

    DOEpatents

    Dijaili, Sol P.; Patterson, Frank G.; Walker, Jeffrey D.; Deri, Robert J.; Petersen, Holly; Goward, William

    2002-01-01

    A highly heat conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient or heat sink. However, the semiconductor material itself should be as temperature insensitive as possible and therefore the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, e.g., a ridge waveguide. The second and most important function, as it relates to this invention, is that it provides a significantly higher thermal conductivity than the semiconductor material, which is the principal material in the fabrication of various optoelectronic devices.

  7. Tunable semiconductor laser at 1025-1095 nm range for OCT applications with an extended imaging depth

    NASA Astrophysics Data System (ADS)

    Shramenko, Mikhail V.; Chamorovskiy, Alexander; Lyu, Hong-Chou; Lobintsov, Andrei A.; Karnowski, Karol; Yakubovich, Sergei D.; Wojtkowski, Maciej

    2015-03-01

    Tunable semiconductor laser for 1025-1095 nm spectral range is developed based on the InGaAs semiconductor optical amplifier and a narrow band-pass acousto-optic tunable filter in a fiber ring cavity. Mode-hop-free sweeping with tuning speeds of up to 104 nm/s was demonstrated. Instantaneous linewidth is in the range of 0.06-0.15 nm, side-mode suppression is up to 50 dB and polarization extinction ratio exceeds 18 dB. Optical power in output single mode fiber reaches 20 mW. The laser was used in OCT system for imaging a contact lens immersed in a 0.5% intra-lipid solution. The cross-section image provided the imaging depth of more than 5mm.

  8. Ultrashort pulse generation from vertical cavity surface emitting semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Jasim, Khalil E.

    This work presents the first demonstration of a passively modelocked extended vertical cavity surface emitting laser (VECSEL) diode. Three cavity configurations were used to sustain stable passive modelocking operation: the Z-shaped, V-shaped and linear cavities. A semiconductor saturable absorber mirror (SESAM) used to triggered passive modelocking of the VECSEL diode. The SESAM device was used as a nonlinear high reflector in the Z-shaped and V-shaped cavity configurations, while it served as an output coupler (SESAMOC) in the linear cavity after the substrate was being angle polished and antireflection coated to eliminate any etalon effects. Many examples of VECSEL diode passive modelocking results will be presented. The standard non-collinear second-harmonic autocorrelation technique has been used to measure the generated pulse width, which was as small as 23 psec. The VECSEL-SESAM configuration has generated stable pulse trains at repetition rates ranging from 1 GHz to approximately 6 GHz, depending on the resonator configuration. Modelocking operation was stable and robust as amplitude noise measurements revealed a noise level ˜0.8%. Moreover, harmonic passive modelocking operation has been observed for the first time during the investigation of modelocking dynamics and stability in the regime of strong self-feedback coupling >10%. A reverse biased p-i-n QW device has enabled the generation of a stable pulse train at 15 GHz with pulse duration close to 15 psec and amplitude noise level ˜0.3%. However, due to design limitations of both the active and passive VECSELs, driving the system to produce repetition rates close to 20 GHz resulted in pulse amplitude variation and an unavoidable DC background. These initial results suggest the possibility of design and fabrication of an integrated or monolithic structure, which may lead to operation of the device at repetition rates beyond 50 GHz with sub-ps pulse durations. Although our VECSEL diode emits 980 nm

  9. Microscopic Foundation and Simulation of Coupled Carrier-Temperature Diffusions in Semiconductor Lasers

    NASA Technical Reports Server (NTRS)

    Li, J.; Ning, Cun-Zheng; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    A typical semiconductor-based optoelectronic device, such as a diode laser, consists of three subsystems: an optical field, an electron-hole plasma (EHP), and a host crystal lattice. The physics of such a device involves the interplay of optical, electrical and thermal processes. A proper description of such a device requires that all three processes are treated on equal footing and in a self-consistent fashion. Furthermore, since a semiconductor laser has intrinsic spatial inhomogeneity, such a self-consistency naturally leads to a set of partial differential equations in space and time. There is a significant lacking of research interest and results on the transport aspects of optical devices in the literature with only a few exceptions. Even the most important carrier diffusion coefficient has not been properly derived and studied so far for optically excited plasma, while most of the work adopted results from electronics community where heavily doped semiconductors with mainly one type of carriers are dealt with. The corresponding transport equation for plasma energy or temperature has received even less attention. In this talk we describe our recent results on such a self-consistent derivation of temperature and carrier-density diffusion equations coupled with the lasing process. Starting from the microscopic semiconductor Bloch equations (SBEs) including the Boltzmann transport terms in the distribution function equations for electrons and holes, we derived a closed set of diffusion equations for carrier densities and temperatures with self-consistent coupling to Maxwell's equation and to an effective optical polarization equation. The coherent many-body effects are included within the screened Hartree-Fock approximation, while scatterings are treated within the second Born approximation including both the in- and out-scatterings. Microscopic expressions for electron-hole (e-h) and carrier-LO (c-LO) phonon scatterings are directly used to derive the momentum

  10. High-sensitivity intracavity laser absorption spectroscopy with vertical-external-cavity surface-emitting semiconductor lasers.

    PubMed

    Garnache, A; Kachanov, A A; Stoeckel, F; Planel, R

    1999-06-15

    We report the demonstration of high-sensitivity intracavity laser absorption spectroscopy with multiple-quantum-well vertical-external-cavity surface-emitting semiconductor lasers (VECSEL's). A detection limit of 3 x 10(-10) cm (-1) has been achieved. The spectrotemporal dynamics of a VECSEL in the 1030-nm wavelength region has been studied. The laser was operating cw at room temperature, with a baseline signal-to-noise ratio as high as 400. The laser was optically pumped with a threshold as low as 80 mW and was broadly tunable over a spectral range of approximately 75 nm .

  11. Semiconductor-based, large-area, flexible, electronic devices on {110}<100> oriented substrates

    SciTech Connect

    Goyal, Amit

    2014-08-05

    Novel articles and methods to fabricate the same resulting in flexible, oriented, semiconductor-based, electronic devices on {110}<100> textured substrates are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  12. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    SciTech Connect

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  13. Noise spectra of a semiconductor ring laser in the bidirectional regime

    SciTech Connect

    Perez-Serrano, Antonio; Zambrini, Roberta; Scire, Alessandro; Colet, Pere

    2009-10-15

    We analytically investigate the influence of complex backscattering coefficients and pump current on the noise spectra of a two-mode model for semiconductor ring laser in the Langevin formulation. The system features in the bidirectional regime are naturally described in terms of the two mode-intensity sum (I spectrum) and difference (D spectrum). The I spectrum reflects the energy exchange between the total field and the medium and behaves similarly to the relative intensity noise for single-mode semiconductor lasers. The D spectrum represents the energy exchange between the two counterpropagating modes and is shaped by the noisy precursor of a Hopf bifurcation induced by the complex backscattering.

  14. Time delay signature concealment of optical feedback induced chaos in an external cavity semiconductor laser.

    PubMed

    Wu, Jia-Gui; Xia, Guang-Qiong; Tang, Xi; Lin, Xiao-Dong; Deng, Tao; Fan, Li; Wu, Zheng-Mao

    2010-03-29

    The time delay (TD) signature concealment of optical feedback induced chaos in an external cavity semiconductor laser is experimentally demonstrated. Both the evolution curve and the distribution map of TD signature are obtained in the parameter space of external feedback strength and injection current. The optimum parameter scope of the TD signature concealment is also specified. Furthermore, the approximately periodic evolution relation between TD signature and external cavity length is observed and indicates that the intrinsic relaxation oscillation of semiconductor laser may play an important role during the process of TD signature suppression.

  15. Final report on LDRD project: Semiconductor surface-emitting microcavity laser spectroscopy for analysis of biological cells and microstructures

    SciTech Connect

    Gourley, P.L.; McDonald, A.E.; Gourley, M.F.; Bellum, J.

    1997-08-01

    This article discusses a new intracavity laser technique that uses living or fixed cells as an integral part of the laser. The cells are placed on a GaAs based semiconductor wafer comprising one half of a vertical cavity surface-emitting laser. After placement, the cells are covered with a dielectric mirror to close the laser cavity. When photo-pumped with an external laser, this hybrid laser emits coherent light images and spectra that depend sensitively on the cell size, shape, and dielectric properties. The light spectra can be used to identify different cell types and distinguish normal and abnormal cells. The laser can be used to study single cells in real time as a cell-biology lab-on-a-chip, or to study large populations of cells by scanning the pump laser at high speed. The laser is well-suited to be integrated with other micro-optical or micro-fluidic components to lead to micro-optical-mechanical systems for analysis of fluids, particulates, and biological cells.

  16. Optically pumped semiconductor lasers: from nonlinear lensing to solar lasers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wilcox, Keith G.; Quarterman, Adrian H.; Smyth, Conor J. C. P.; Mirkhanov, Shamil

    2017-03-01

    We report on recent developments in the characterisation of non-linear lensing in semiconductor disk laser gain samples. We find that there is a significant nonlinear lens present and the magnitude and sign of this depend on the conditions under which it is being observed. Under experimental conditions which are, to date, the closest to intra-cavity conditions, with 350 fs pulses at the same wavelength a mode-locked SDL using that gain chip would operate at we find that the lens is always negative and its magnitude is almost independent of pump intensity. We also report on the experimental observation of different mode-locking regimes in SDLs including dual wavelength mode-locking and pulse molecule formation and compare these experimentally observed modes of operation with predictions from microscopic modelling previously reported in by Kilen et. al. [1] [1] I. Kilen et. al. Optica, 1 (4) 192-197 (2014)

  17. Dynamic behaviors of semiconductor lasers under strong sinusoidal current modulation; Modeling and experiments at 1. 3. mu. m

    SciTech Connect

    Hemery, E. ); Chusseau, L.; Lourtioz, J.M. )

    1990-04-01

    A theoretical and experimental study of the dynamic behaviors of semiconductor lasers under strong sinusoidal modulation is presented. The theoretical analysis is based on rate-equations including gain-compression effects. General criteria are established to predict the existence of irregular behaviors. Experiments are performed on a single-mode buried-heterostructure InGaAsP laser at 1.3 {mu}m. An original method is proposed to evaluate the parameters entering the rate equations. Fully optical measurements are used. The nonlinear gain coefficient and the electrical response of the packaged laser are simultaneously determined from small-signal characteristics. Time-domain measurements show the three behaviors achieved with the studied laser, i.e., simple periodic, periodic with multiple spikes, and period doubling.

  18. Curved grating fabrication techniques for concentric-circle grating, surface-emitting semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Jordan, Rebecca H.; King, Oliver; Wicks, Gary W.; Hall, Dennis G.; Anderson, Erik H.; Rooks, Michael J.

    1993-01-01

    We describe the fabrication and operational characteristics of a novel, surface-emitting semiconductor laser that makes use of a concentric-circle grating to both define its resonant cavity and to provide surface emission. A properly fabricated circular grating causes the laser to operate in radially inward- and outward-going circular waves in the waveguide, thus, introducing the circular symmetry needed for the laser to emit a beam with a circular cross-section. The basic circular-grating-resonator concept can be implemented in any materials system; an AlGaAs/GaAs graded-index, separate confinement heterostructure (GRINSCH), single-quantum-well (SQW) semiconductor laser, grown by molecular beam epitaxy (MBE), was used for the experiments discussed here. Each concentric-circle grating was fabricated on the surface of the AlGaAs/GaAs semiconductor laser. The circular pattern was first defined by electron-beam (e-beam) lithography in a layer of polymethylmethacrylate (PMMA) and subsequently etched into the semiconductor surface using chemically-assisted (chlorine) ion-beam etching (CAIBE). We consider issues that affect the fabrication and quality of the gratings. These issues include grating design requirements, data representation of the grating pattern, and e-beam scan method. We provide examples of how these techniques can be implemented and their impact on the resulting laser performance. A comparison is made of the results obtained using two fundamentally different electron-beam writing systems. Circular gratings with period lambda = 0.25 microns and overall diameters ranging from 80 microns to 500 microns were fabricated. We also report our successful demonstration of an optically pumped, concentric-circle grating, semiconductor laser that emits a beam with a far-field divergence angle that is less than one degree. The emission spectrum is quite narrow (less than 0.1 nm) and is centered at wavelength lambda = 0.8175 microns.

  19. The optical effect of a semiconductor laser on protecting wheat from UV-B radiation damage.

    PubMed

    Qiu, Zong-Bo; Zhu, Xin-Jun; Li, Fang-Min; Liu, Xiao; Yue, Ming

    2007-07-01

    Lasers have been widely used in the field of biology along with the development of laser technology, but the mechanism of the bio-effect of lasers is not explicit. The objective of this paper was to test the optical effect of a laser on protecting wheat from UV-B damage. A patent instrument was employed to emit semiconductor laser (wavelength 650 nm) and incoherent red light, which was transformed from the semiconductor laser. The wavelength, power and lightfleck diameter of the incoherent red light are the same as those of the semiconductor laser. The semiconductor laser (wavelength 650 nm, power density 3.97 mW mm(-2)) and incoherent red light (wavelength 650 nm, power density 3.97 mW mm(-2)) directly irradiated the embryo of wheat seeds for 3 min respectively, and when the seedlings were 12-day-old they were irradiated by UV-B radiation (10.08 kJ m(-2)) for 12 h in the dark. Changes in the concentration of malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), glutathione (GSH), ascorbate (AsA), carotenoids (CAR), the production rate of superoxide radical (O(2)(-)), the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and the growth parameters of seedlings (plant height, leaf area and fresh weight) were measured to test the optical effect of the laser. The results showed that the incoherent red light treatment could not enhance the activities of SOD, POD and CAT and the concentration of AsA and CAR. When the plant cells were irradiated by UV-B, the incoherent red light treatment could not eliminate active oxygen and prevent lipid peroxidation in wheat. The results also clearly demonstrate that the plant DNA was damaged by UV-B radiation and semiconductor laser irradiance had the capability to protect plants from UV-B-induced DNA damage, while the incoherent red light could not. This is the first investigation reporting the optical effect of a semiconductor laser on protecting wheat from UV-B radiation damage.

  20. Evolution of the Novalux extended cavity surface-emitting semiconductor laser (NECSEL)

    NASA Astrophysics Data System (ADS)

    McInerney, John G.

    2016-03-01

    Novalux Inc was an enterprise founded by Aram Mooradian in 1998 to commercialise a novel electrically pumped vertical extended cavity semiconductor laser platform, initially aiming to produce pump lasers for optical fiber telecommunication networks. Following successful major investment in 2000, the company developed a range of single- and multi-mode 980 nm pump lasers emitting from 100-500 mW with excellent beam quality and efficiency. This rapid development required solution of several significant problems in chip and external cavity design, substrate and DBR mirror optimization, thermal engineering and mode selection. Output coupling to single mode fiber was exceptional. Following the collapse of the long haul telecom market in late 2001, a major reorientation of effort was undertaken, initially to develop compact 60-100 mW hybrid monolithically integrated pumplets for metro/local amplified networks, then to frequency-doubled blue light emitters for biotech, reprographics and general scientific applications. During 2001-3 I worked at Novalux on a career break from University College Cork, first as R&D Director managing a small group tasked with producing new capabilities and product options based on the NECSEL platform, including high power, pulsed and frequency doubled versions, then in 2002 as Director of New Product Realization managing the full engineering team, leading the transition to frequency doubled products.

  1. Thermal Property Measurement of Semiconductor Melt using Modified Laser Flash Method

    NASA Technical Reports Server (NTRS)

    Lin, Bochuan; Zhu, Shen; Ban, Heng; Li, Chao; Scripa, Rosalla N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2003-01-01

    This study further developed standard laser flash method to measure multiple thermal properties of semiconductor melts. The modified method can determine thermal diffusivity, thermal conductivity, and specific heat capacity of the melt simultaneously. The transient heat transfer process in the melt and its quartz container was numerically studied in detail. A fitting procedure based on numerical simulation results and the least root-mean-square error fitting to the experimental data was used to extract the values of specific heat capacity, thermal conductivity and thermal diffusivity. This modified method is a step forward from the standard laser flash method, which is usually used to measure thermal diffusivity of solids. The result for tellurium (Te) at 873 K: specific heat capacity 300.2 Joules per kilogram K, thermal conductivity 3.50 Watts per meter K, thermal diffusivity 2.04 x 10(exp -6) square meters per second, are within the range reported in literature. The uncertainty analysis showed the quantitative effect of sample geometry, transient temperature measured, and the energy of the laser pulse.

  2. Chaos and noise control by current modulation in semiconductor lasers subject to optical feedback

    NASA Astrophysics Data System (ADS)

    Ahmed, M.; El-Sayed, N. Z.; Ibrahim, H.

    2012-05-01

    This paper introduces comprehensive large-signal analyses of modulation dynamics and noise of a chaotic semiconductor laser. The chaos is induced by operating the laser under optical feedback (OFB). Control of the chaotic dynamics and possibility of suppressing the associated noise by sinusoidal modulation are investigated. The studies are based on numerical solutions of a time-delay rate equation model. The deterministic modulation dynamics of the laser are classified into seven regular and irregular dynamic types. Variations of chaotic dynamics and noise with sinusoidal modulation are examined in both time and frequency domains over wide ranges of the modulation depth and frequency. The results showed that chaotic dynamics can be converted into five distinct dynamic types; namely, continuous periodic signal (CPS), continuous periodic signal with relaxation oscillations (CPSRO), periodic pulse (PP), periodic pulse with relaxation oscillations (PPRO) and periodic pulse with period doubling (PPPD). The relative intensity noise (RIN) of these types is characterized when the modulation frequencies are much lower, comparable to, and higher than the resonance frequency. Suppression of RIN to a level 8 dB/Hz higher than the quantum limit was predicted under the CPS type when the modulation frequency is 0.9 times the resonance frequency and the modulation depth is 0.14.

  3. Modification of semiconductor materials using laser-produced ion streams additionally accelerated in the electric fields

    NASA Astrophysics Data System (ADS)

    Rosinski, M.; Badziak, B.; Parys, P.; Wołowski, J.; Pisarek, M.

    2009-03-01

    The laser-produced ion stream may be attractive for direct ultra-low-energy ion implantation in thin layer of semiconductor for modification of electrical and optical properties of semiconductor devices. Application of electrostatic fields for acceleration and formation of laser-generated ion stream enables to control the ion stream parameters in broad energy and current density ranges. It also permits to remove the useless laser-produced ions from the ion stream designed for implantation. For acceleration of ions produced with the use of a low fluence repetitive laser system (Nd:glass: 2 Hz, pulse duration: 3.5 ns, pulse energy:˜0.5 J, power density: 10 10 W/cm 2) in IPPLM the special electrostatic system has been prepared. The laser-produced ions passing through the diaphragm (a ring-shaped slit in the HV box) have been accelerated in the system of electrodes. The accelerating voltage up to 40 kV, the distance of the diaphragm from the target, the diaphragm diameter and the gap width were changed for choosing the desired parameters (namely the energy band of the implanted ions) of the ion stream. The characteristics of laser-produced Ge ion streams were determined with the use of precise ion diagnostic methods, namely: electrostatic ion energy analyser and various ion collectors. The laser-produced and post-accelerated Ge ions have been used for implantation into semiconductor materials for nanocrystal fabrication. The characteristics of implanted samples were measured using AES.

  4. Spectral characteristics of distributed feedback semiconductor laser and their improvements by corrugation-pitch-modulated structure

    NASA Astrophysics Data System (ADS)

    Okai, Makoto

    1994-01-01

    This paper presents a review of a theoretical analysis problems that occur with single-mode lasers, and a novel laser structure for superstable single-mode operation. Also presented is a new grating-fabrication technique termed photo-mask self-interference, to fabricate corrugation-pitch-modulated (CPM) structures, for enhancing the stability of the longitudinal single-mode operation in distributed feedback lasers (DFB). It is seen that the CPM-DFB laser developed for coherent transmission systems displays the narrowest spectral linewidth (56 kHz) reported so far for a semiconductor.

  5. Rate equations analysis of phase-locked semiconductor laser arrays under steady state conditions

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Rate equations analysis of phase-locked semiconductor laser arrays has been carried out. It was found that for given (laser) current densities, the photon density distribution in the array elements is that particular one which maximizes the total photon density. The results of this analysis were then combined with the waveguide properties of the laser array waveguide, yielding a basic model of phase-locked diode laser arrays. This model explains the effects of the variation of the current combination through the array elements on its mode structure that were observed recently.

  6. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, Raymond J.; Benett, William J.; Mills, Steven T.

    1997-01-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a "rack and stack" configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber.

  7. Fiber optic coupling of a microlens conditioned, stacked semiconductor laser diode array

    DOEpatents

    Beach, R.J.; Benett, W.J.; Mills, S.T.

    1997-04-01

    The output radiation from the two-dimensional aperture of a semiconductor laser diode array is efficiently coupled into an optical fiber. The two-dimensional aperture is formed by stacking individual laser diode bars on top of another in a ``rack and stack`` configuration. Coupling into the fiber is then accomplished using individual microlenses to condition the output radiation of the laser diode bars. A lens that matches the divergence properties and wavefront characteristics of the laser light to the fiber optic is used to focus this conditioned radiation into the fiber. 3 figs.

  8. Diffraction-Coupled, Phase-Locked Semiconductor Laser Array

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Yariv, Amnon; Margalit, Shlomo

    1988-01-01

    Stable, narrow far field produced. Array of lasers fabricated on single chip. Individual laser waveguides isolated from each other except in end portions, where diffraction coupling takes place. Radiation pattern far from laser array has single, sharp central lobe when all lasers operate in phase with each other. Shape of lobe does not vary appreciably with array current. Applications include recording, printing, and range finding.

  9. Tolerances for Phase Locking of Semiconductor Laser Arrays.

    DTIC Science & Technology

    1988-04-18

    laser fabrication . This means that the starting material is critically important to tne success of locked laser arrays. F. TOLERANCE REQUIREMENTS ON...typically r , 0.1. Because Eq. (7) represents a small frequency deviation, and implies A - 0.5 4, this report will look into the tolerances on laser ... fabrication and operation to ensure that the free-running laser frequencies remain within this locking range. D. COMPARISON OF LOCKING CONDITION WITH

  10. Theoretical analysis of a method for extracting the phase of a phase-amplitude modulated signal generated by a direct-modulated optical injection-locked semiconductor laser

    NASA Astrophysics Data System (ADS)

    Lee, Hwan; Cho, Jun-Hyung; Sung, Hyuk-Kee

    2017-05-01

    The phase modulation (PM) and amplitude modulation (AM) of optical signals can be achieved using a direct-modulated (DM) optical injection-locked (OIL) semiconductor laser. We propose and theoretically analyze a simple method to extract the phase component of a PM signal produced by a DM-OIL semiconductor laser. The pure AM component of the combined PM-AM signal can be isolated by square-law detection in a photodetector and can then be used to compensate for the PM-AM signal based on an optical homodyne method. Using the AM compensation technique, we successfully developed a simple and cost-effective phase extraction method applicable to the PM-AM optical signal of a DM-OIL semiconductor laser.

  11. Experimental study and chemical application of GaAs semiconductor laser treating trigeminal neuralgia

    NASA Astrophysics Data System (ADS)

    Qiu, Ke-Qum; Cao, Shu-Chen; Wang, Hu-Zhong; Wang, Ke-Ning; Xiao, Ton-Ha; Shen, Ke-Wei

    1993-03-01

    GaAs semiconductor laser was used to treat trigeminal neuralgia with an effective rate of 91.1%, and no side effects were found in 67 cases. Changes in and the recovery of the trigeminal nerve cell were studied with light and electromicroscope. Discussed in this article are the time length and quantity of laser treatment with low power. Experimental study and clinical application of the GaAs semiconductor laser have been carried out in our department since 1987. One-hundred-fifteen patients with various diseases in the maxillofacial region (including 67 cases of trigeminal neuralgia) have been treated with satisfactory effects and without any side-effects. The wavelength of the laser is 904 mu, the largest pulse length is 200 mu, and the average power is 2000 HZ.

  12. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOEpatents

    Hohimer, John P.

    1994-01-01

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure.

  13. Semiconductor diode laser having an intracavity spatial phase controller for beam control and switching

    DOEpatents

    Hohimer, J.P.

    1994-06-07

    A high-power broad-area semiconductor laser having a intracavity spatial phase controller is disclosed. The integrated intracavity spatial phase controller is easily formed by patterning an electrical contact metallization layer when fabricating the semiconductor laser. This spatial phase controller changes the normally broad far-field emission beam of such a laser into a single-lobed near-diffraction-limited beam at pulsed output powers of over 400 mW. Two operating modes, a thermal and a gain operating mode, exist for the phase controller, allowing for steering and switching the beam as the modes of operation are switched, and the emission beam may be scanned, for example, over a range of 1.4 degrees or switched by 8 degrees. More than one spatial phase controller may be integrated into the laser structure. 6 figs.

  14. High-coherent-power, two-dimensional grating surface-emitting (GSE) semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Li, Shuang

    High-power semiconductor lasers, with coherent radiation, are attractive sources for many applications. However, achieving stable, coherent radiation to watt-range power from monolithic semiconductor lasers has been a challenge. This work covers the study and development of high power coherent semiconductor lasers employing novel-types of both surface-emitting and edge-emitting structures. Surface-emitting (SE) semiconductor lasers are preferred over edge-emitting lasers due to their inherent reliability, scalability, and packaging advantages. Horizontal-cavity, grating SE semiconductor lasers are promising candidates for high-power coherent sources. Here we present the design and analysis of a two-dimensional (2D) horizontal-cavity GSE laser (so called ROW-SEDFB laser), for which 2nd-order, distributed feedback/distributed Bragg reflector (DFB/DBR) gratings with central pi phaseshift are preferentially placed in the element regions of a resonant-optical-waveguide (ROW) structure. We find that beside their usual functions (feedback and outcoupling), the gratings act as an effective array-mode selector. The in-phase mode is strongly favored to lase around its resonance due both to better field overlap with the active-grating (i.e., DFB) and to lower interelement loss than the other array modes. For 20-element arrays with 700/600mum-long DFB/DBR gratings, and of 100mum-wide lateral dimension, high intermodal discrimination is obtained. The primary mechanisms behind this discrimination are found to be: absorption losses for the interelement field to the metal contact and to a semiconductor/metal grating layer, and the longitudinal guided-field overlap with the DFB region. The discrimination can be further enhanced by introducing free-carrier absorption in the interelement regions. The device has relatively uniform guided-field profiles in both lateral and longitudinal directions and a strong built-in index profile in the lateral direction. These features make the ROW

  15. A biological semiconductor based on electrical percolation

    PubMed Central

    Yang, Minghui; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

    2010-01-01

    We have developed a novel biological semiconductor (BSC) based on electrical percolation through a multi-layer 3-D carbon nanotube-antibody network, which can measure biological interactions directly and electronically. In Electrical Percolation, the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. A BSC is fabricated by immobilizing a pre-functionalized single-walled carbon nanotubes (SWNTs)-antibody complex directly on a Poly(methyl methacrylate) (PMMA) surface (also known as plexi-glass or Acrylic). We used the BSC for direct (label-free) electronic measurements of antibody-antigen binding, showing that, at slightly above the electrical percolation threshold of the network, binding of a specific antigen dramatically increases the electrical resistance. Using anti-Staphylococcal enterotoxin B (SEB) IgG as a “gate” and SEB as an “actuator”, we demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/ml. The new BSCs may permit assembly of multiple sensors on the same chip to create “Biological Central Processing Units (CPUs)” with multiple biological elements, capable of processing and sorting out information on multiple analytes simultaneously. PMID:20361741

  16. Biological semiconductor based on electrical percolation.

    PubMed

    Yang, Minghui; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

    2010-05-01

    We have developed a novel biological semiconductor (BSC) based on electrical percolation through a multilayer three-dimensional carbon nanotube-antibody bionanocomposite network, which can measure biological interactions directly and electronically. In electrical percolation, the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. A BSC is fabricated by immobilizing a prefunctionalized single-walled carbon nanotubes (SWNTs)-antibody bionanocomposite directly on a poly(methyl methacrylate) (PMMA) surface (also known as plexiglass or acrylic). We used the BSC for direct (label-free) electronic measurements of antibody-antigen binding, showing that, at slightly above the electrical percolation threshold of the network, binding of a specific antigen dramatically increases the electrical resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG as a "gate" and SEB as an "actuator", we demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/mL. The new BSCs may permit assembly of multiple sensors on the same chip to create "biological central processing units (CPUs)" with multiple BSC elements, capable of processing and sorting out information on multiple analytes simultaneously.

  17. Spatial distribution of the intensity noise of a vertical-cavity surface-emitting semiconductor laser.

    PubMed

    Bramati, A; Hermier, J P; Khoury, A Z; Giacobino, E; Schnitzer, P; Michalzik, R; Ebeling, K J; Poizat, J P; Grangier, P

    1999-07-01

    We studied anticorrelated quantum fluctuations between the TEM(00) and the TEM(01) transverse modes of a vertical-cavity surface-emitting semiconductor laser by measuring the transverse spatial distribution of the laser beam intensity noise. Our experimental results are found to be in good agreement with the predictions of a phenomenological model that accounts for quantum correlations between transverse modes in a light beam.

  18. GaAs/GaInP double heterostructure characterization for laser cooling of semiconductors

    NASA Astrophysics Data System (ADS)

    Wang, Chengao; Li, Chia-Yeh; Hasselbeck, Michael P.; Rotter, Thomas; Malloy, Kevin; Sheik-Bahae, Mansoor; Olson, Jerry

    2011-03-01

    External quantum efficiency of semiconductor photonic devices is directly measured by wavelength-dependent laser-induced temperature change (scanning laser calorimetry) with very high accuracy. Maximum efficiency is attained at an optimum photo-excitation level that can be determined with an independent measurement of power-dependent photoluminescence. Differential power-dependent photoluminescence measurement is used to quickly screen the sample quality before processing.

  19. Dynamical Slowing and trapping of light in coupled semiconductor laser arrays.

    PubMed

    Yifat, Yuval; Scheuer, Jacob

    2009-09-28

    We propose and analyze a new scheme for storing and releasing optical pulses comprising an array of weakly coupled semiconductor lasers. By activating and deactivating individual lasers in the array we are able to manipulate optical pulses, trap them for long periods and release them without noticeable distortion. In addition, the proposed scheme can also regenerate and reshape distorted pulses all-optically. Additional applications such as routing, pulse synchronization and true-time-delaying are also presented and discussed.

  20. Time-resolved studies of a rolled-up semiconductor microtube laser

    NASA Astrophysics Data System (ADS)

    Strelow, Ch.; Sauer, M.; Fehringer, S.; Korn, T.; Schüller, C.; Stemmann, A.; Heyn, Ch.; Heitmann, D.; Kipp, T.

    2009-11-01

    We report on lasing in rolled-up microtube resonators. Time-resolved studies on these semiconductor lasers containing GaAs quantum wells as optical gain material reveal particularly fast turn-on times and short pulse emissions above the threshold. We observe a strong redshift of the laser mode during the pulse emission which is compared to the time evolution of the charge-carrier density calculated by rate equations.

  1. Simple laser velocimeter that uses photoconductive semiconductors to measure optical frequency differences.

    PubMed

    Wang, C C; Davidson, F; Trivedi, S

    1995-10-01

    The dc photocurrents generated by steady-state moving space-charge fields inside photoconductive semiconductors containing deep level donors and traps can be used to determine the relative frequency differences between the two interfering optical fields that establish the space-charge fields. A simple laser velocimeter that uses a semi-insulating GaAs:Cr sample to detect the Doppler frequency shift between two laser beams is demonstrated.

  2. Monolithic integration of widely tunable sampled grating DBR laser with tilted semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Nan, Ye; Baojun, Wang; Daibing, Zhou; Xin, An; Jing, Bian; Jiaoqing, Pan; Lingjuan, Zhao; Wei, Wang

    2010-07-01

    High output powers and wide range tuning have been achieved in a sampled grating distributed Bragg reflector laser with an integrated semiconductor optical amplifier. Tilted amplifier and anti-reflection facet coating are used to suppress reflection. We have demonstrated sampled grating DBR laser with a tuning range over 38 nm, good wavelength coverage and peak output powers of more than 9 mW for all wavelengths.

  3. Saturated semiconductor optical amplifier phase modulation for long range laser radar applications.

    PubMed

    Carns, Jennifer L; Duncan, Bradley D; Dierking, Matthew P

    2012-08-20

    We investigate the use of a semiconductor optical amplifier operated in the saturation regime as a phase modulator for long range laser radar applications. The nature of the phase and amplitude modulation resulting from a high peak power Gaussian pulse, and the impact this has on the ideal pulse response of a laser radar system, is explored. We also present results of a proof-of-concept laboratory demonstration using phase-modulated pulses to interrogate a stationary target.

  4. Welding of Semiconductor Nanowires by Coupling Laser-Induced Peening and Localized Heating

    NASA Astrophysics Data System (ADS)

    Rickey, Kelly M.; Nian, Qiong; Zhang, Genqiang; Chen, Liangliang; Suslov, Sergey; Bhat, S. Venkataprasad; Wu, Yue; Cheng, Gary J.; Ruan, Xiulin

    2015-11-01

    We demonstrate that laser peening coupled with sintering of CdTe nanowire films substantially enhances film quality and charge transfer while largely maintaining basic particle morphology. During the laser peening phase, a shockwave is used to compress the film. Laser sintering comprises the second step, where a nanosecond pulse laser beam welds the nanowires. Microstructure, morphology, material content, and electrical conductivities of the films are characterized before and after treatment. The morphology results show that laser peening can decrease porosity and bring nanowires into contact, and pulsed laser heating fuses those contacts. Multiphysics simulations coupling electromagnetic and heat transfer modules demonstrate that during pulsed laser heating, local EM field enhancement is generated specifically around the contact areas between two semiconductor nanowires, indicating localized heating. The characterization results indicate that solely laser peening or sintering can only moderately improve the thin film quality; however, when coupled together as laser peen sintering (LPS), the electrical conductivity enhancement is dramatic. LPS can decrease resistivity up to a factor of ~10,000, resulting in values on the order of ~105 Ω-cm in some cases, which is comparable to CdTe thin films. Our work demonstrates that LPS is an effective processing method to obtain high-quality semiconductor nanocrystal films.

  5. Welding of Semiconductor Nanowires by Coupling Laser-Induced Peening and Localized Heating

    PubMed Central

    Rickey, Kelly M.; Nian, Qiong; Zhang, Genqiang; Chen, Liangliang; Suslov, Sergey; Bhat, S. Venkataprasad; Wu, Yue; Cheng, Gary J.; Ruan, Xiulin

    2015-01-01

    We demonstrate that laser peening coupled with sintering of CdTe nanowire films substantially enhances film quality and charge transfer while largely maintaining basic particle morphology. During the laser peening phase, a shockwave is used to compress the film. Laser sintering comprises the second step, where a nanosecond pulse laser beam welds the nanowires. Microstructure, morphology, material content, and electrical conductivities of the films are characterized before and after treatment. The morphology results show that laser peening can decrease porosity and bring nanowires into contact, and pulsed laser heating fuses those contacts. Multiphysics simulations coupling electromagnetic and heat transfer modules demonstrate that during pulsed laser heating, local EM field enhancement is generated specifically around the contact areas between two semiconductor nanowires, indicating localized heating. The characterization results indicate that solely laser peening or sintering can only moderately improve the thin film quality; however, when coupled together as laser peen sintering (LPS), the electrical conductivity enhancement is dramatic. LPS can decrease resistivity up to a factor of ~10,000, resulting in values on the order of ~105 Ω-cm in some cases, which is comparable to CdTe thin films. Our work demonstrates that LPS is an effective processing method to obtain high-quality semiconductor nanocrystal films. PMID:26527570

  6. Semiconductor surface emitting lasers for photon pairs generation

    NASA Astrophysics Data System (ADS)

    Vanbever, Luc R.; Karpov, Evgueni; Panajotov, Krassimir

    2017-10-01

    We study the feasibility of generating photon pairs in a resonant Vertical-Cavity Surface-Emitting Laser (VCSEL) as a result of a third-order non-linear, four wave mixing interaction. We focus on degenerate four wave mixing in the spontaneous regime where two pump photons are annihilated to create a pair of signal and idler photons. Using the methods of quantum optics, we calculate the two-photon production rate, the spectrum of the generated photons, and the signal-idler cross-correlations. We highlight how the dispersion of the medium in the VCSEL cavity (a regular GaAs configuration) significantly diminishes the two-photon production rate. Based on our results, we enumerate the characteristics of a VCSEL that would be suitable for photon pair generation.

  7. Electrically pumped semiconductor laser with monolithic control of circular polarization

    PubMed Central

    Rauter, Patrick; Lin, Jiao; Genevet, Patrice; Khanna, Suraj P.; Lachab, Mohammad; Giles Davies, A.; Linfield, Edmund H.; Capasso, Federico

    2014-01-01

    We demonstrate surface emission of terahertz (THz) frequency radiation from a monolithic quantum cascade laser with built-in control over the degree of circular polarization by “fishbone” gratings composed of orthogonally oriented aperture antennas. Different grating concepts for circularly polarized emission are introduced along with the presentation of simulations and experimental results. Fifth-order gratings achieve a degree of circular polarization of up to 86% within a 12°-wide core region of their emission lobes in the far field. For devices based on an alternative transverse grating design, degrees of circular polarization as high as 98% are demonstrated for selected far-field regions of the outcoupled THz radiation and within a collection half-angle of about 6°. Potential and limitations of integrated antenna gratings for polarization-controlled emission are discussed. PMID:25512515

  8. Electrically pumped semiconductor laser with monolithic control of circular polarization.

    PubMed

    Rauter, Patrick; Lin, Jiao; Genevet, Patrice; Khanna, Suraj P; Lachab, Mohammad; Giles Davies, A; Linfield, Edmund H; Capasso, Federico

    2014-12-30

    We demonstrate surface emission of terahertz (THz) frequency radiation from a monolithic quantum cascade laser with built-in control over the degree of circular polarization by "fishbone" gratings composed of orthogonally oriented aperture antennas. Different grating concepts for circularly polarized emission are introduced along with the presentation of simulations and experimental results. Fifth-order gratings achieve a degree of circular polarization of up to 86% within a 12°-wide core region of their emission lobes in the far field. For devices based on an alternative transverse grating design, degrees of circular polarization as high as 98% are demonstrated for selected far-field regions of the outcoupled THz radiation and within a collection half-angle of about 6°. Potential and limitations of integrated antenna gratings for polarization-controlled emission are discussed.

  9. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking.

    PubMed

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J; Grillot, Frédéric

    2016-06-15

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%.

  10. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  11. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking

    PubMed Central

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J.; Grillot, Frédéric

    2016-01-01

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%. PMID:27302301

  12. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  13. Monolithic integration of widely tunable sampled grating DBR laser with tilted semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Ye, Nan; Liu, Yang; Wang, Baojun; Zhou, Daibing; Pang, Jiaoqing; Zhao, Lingjuan; Wang, Wei

    2010-12-01

    More than 11mW output powers for all wavelengths from the fiber and over 49 nm range tuning in sampled grating distributed Bragg reflector laser with an integrated semiconductor optical amplifier which is enabling access to 110 ITU 50GHz channels is demonstrated. Tilted amplifier and anti-reflection facet coating are used to suppress reflection.

  14. Monolithic integration of widely tunable sampled grating DBR laser with tilted semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Ye, Nan; Liu, Yang; Wang, BaoJun; Zhou, DaiBing; Pang, JiaoQing; Zhao, LingJuan; Wang, Wei

    2011-01-01

    More than 11mW output powers for all wavelengths from the fiber and over 49 nm range tuning in sampled grating distributed Bragg reflector laser with an integrated semiconductor optical amplifier which is enabling access to 110 ITU 50GHz channels is demonstrated. Tilted amplifier and anti-reflection facet coating are used to suppress reflection.

  15. GaAlAs gain-guided semiconductor lasers with a curved facet

    SciTech Connect

    Yamashita, S.; Nakatsuka, S.; Tanaka, T.; Ono, Y.; Chinone, N.; Kajimura, T.

    1987-11-23

    GaAlAs gain-guided semiconductor lasers having a curved facet are fabricated by employing reactive ion beam etching. The use of the curved facet permits stabilization of transverse mode in the direction parallel to the junction plane, reduction of astigmatism, and multilongitudinal mode oscillation.

  16. Semiconductor photoelectrochemistry

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. M.; Byvik, C. E.

    1983-01-01

    Semiconductor photoelectrochemical reactions are investigated. A model of the charge transport processes in the semiconductor, based on semiconductor device theory, is presented. It incorporates the nonlinear processes characterizing the diffusion and reaction of charge carriers in the semiconductor. The model is used to study conditions limiting useful energy conversion, specifically the saturation of current flow due to high light intensity. Numerical results describing charge distributions in the semiconductor and its effects on the electrolyte are obtained. Experimental results include: an estimate rate at which a semiconductor photoelectrode is capable of converting electromagnetic energy into chemical energy; the effect of cell temperature on the efficiency; a method for determining the point of zero zeta potential for macroscopic semiconductor samples; a technique using platinized titanium dioxide powders and ultraviolet radiation to produce chlorine, bromine, and iodine from solutions containing their respective ions; the photoelectrochemical properties of a class of layered compounds called transition metal thiophosphates; and a technique used to produce high conversion efficiency from laser radiation to chemical energy.

  17. Life prediction of 808nm high power semiconductor laser by accelerated life test of constant current stress

    NASA Astrophysics Data System (ADS)

    Yao, Nan; Li, Wei; Zhao, Yihao; Zhong, Li; Liu, Suping; Ma, Xiaoyu

    2015-10-01

    High power semiconductor laser is widely used because of its high transformation efficiency, good working stability, compact volume and simple driving requirements. Laser's lifetime is very long, but tests at high levels of stress can speed up the failure process and shorten the times to failure significantly. So accelerated life test is used here for forecasting the lifetime of 808nm CW GaAs/AlGaAs high power semiconductor laser that has an output power of 1W under 1.04A. Accelerated life test of constant current stress based on the Inverse Power Law Relationship was designed. Tests were conducted under 1.3A, 1.6A and 1.9A at room temperature. It is the first time that this method is used in the domestic research of laser's lifetime prediction. Applying Weibull Distribution to describe the lifetime distribution and analyzing the data of times to failure, characteristics lifetime's functional relationship model with current is achieved. Then the characteristics lifetime under normal current is extrapolated, which is 9473h. Besides, to confirm the validity of the functional relationship model, we conduct an additional accelerated life test under 1.75A. Based on this experimental data we calculated the characteristics lifetime corresponding to 1.75A that is 171h, while the extrapolated characteristics lifetime from the former functional relationship model is 162h. The two results shows 5% deviation that is very low and acceptable, which indicates that the test design is reasonable and authentic.

  18. Effect of light backscattering on high-speed modulation performance in strongly injection-locked unidirectional semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Smolyakov, Gennady A.; Osinski, Marek

    2014-03-01

    Greatly enhanced high-speed modulation performance has been recently predicted in numerical calculations for a novel injection-locking scheme involving a DBR or DFB master laser monolithically integrated with a unidirectional semiconductor microring laser. In this work, we investigate the effect of light backscattering between the two counterpropagating modes on high-speed modulation performance of strongly injection-locked unidirectional semiconductor microring lasers.

  19. Laser Spectroscopy of Small Metal and Semiconductor Molecules

    NASA Astrophysics Data System (ADS)

    Winstead, Christopher Brooks

    1995-01-01

    An apparatus consisting of a laser vaporization cluster source coupled to a time-of-flight mass spectrometer has been implemented to facilitate the mass-selected spectroscopy of small silver and silicon molecules. Resonantly enhanced multiphoton ionization (REMPI) studies have revealed a previously unknown silver dimer excited electronic state via a forbidden transition near 46870 cm^ {-1}. This state lies in near perfect double resonance with the lower energy A ^1 Sigma_sp{rm u}{+}( rm v^' = 3) >= X ^Sigma_sp{rm g}{+}({rm v^{' '}} = 0) transition, leading to an anomalously large single color Ag_2 ionization signal near 426.7 nm. Symmetry selection rules allow an identification of the new state symmetry as 1_{rm g} or 0 _sp{rm g}{+}. Additional REMPI investigations of the A ^1Sigma _sp{rm u}{+} >=ts X ^1Sigma_sp {rm g}{+} transition yield a new measurement of the Ag_2 ionization potential (IP) and resolve a discrepancy in the reported Ag_2 IP values. The importance of field ionization effects on the observed REMPI spectra is also demonstrated. The spectroscopy of the H ^3Sigma _sp{rm u}{-} state of silicon dimer has been investigated using a combination of laser induced fluorescence and resonant two-photon ionization techniques. Measurements of the isotope induced bandhead shifts for the Si_2 H ^3 Sigma_sp{rm u}{-} >=ts X ^3Sigma_sp {rm g}{-} transition reveal that the previously accepted vibrational numbering of the H ^3Sigma_sp{rm u}{-} state is incorrect. Revised molecular constants based on the new vibrational numbering scheme are T_{rm e} = 24151.86 cm^{-1}, omega_{rm e} = 279.28 cm^{-1}, omega _{rm e}chi_{rm e} = 1.99 cm^{-1} , B_{rm e} = 0.17255 cm^{-1}, and alpha_{rm e} = 0.00135 cm^{-1}. A comparison of experimentally obtained and simulated dispersed laser induced fluorescence spectra demonstrates the improved accuracy of these new constants. Resonant two-photon ionization studies of the H ^3Sigma_sp {rm u}{-} state have also allowed the most accurate

  20. Integrated Linewidth Reduction of Rapidly Tunable Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Sivananthan, Abirami

    Widely tunable lasers with fast tuning speeds have applications in dense wavelength division multiplexing (DWDM), optical sensing and optical packet switching. In DWDM, tunable lasers can greatly reduce inventory costs, increase manufacturing efficiency, and increase flexibility. For this application, tunable lasers must meet stringent requirements in terms of linewidth, SMSR, RIN, etc. As coherent detection moves to higher modulation formats to increase spectral efficiency, linewidths on the order of 100 kHz will be required. In FMCW LIDAR, the sensing range is directly coupled to the coherence length, i.e. linewidth, of the laser, and the resolution is determined by the tuning range of the laser. A laser with a 40 nm tuning range and 100 kHz linewidth can lead to a LIDAR system with 30 microm of resolution at a 1.5 km range. The above motivations demonstrate the need for a laser that is widely tunable, with tuning speeds in the nanosecond regime, a 100 kHz linewidth and small form factor. Many different approaches have been taken to achieve a low linewidth laser, generally with the trade-off of slower tuning speeds or larger size. Typically, the widely tunable mirrors used to create a highly agile laser are noisy. In our approach we use negative feedback along with an InGaAsP/InP photonic integrated circuit (PIC) to reduce the linewidth of a widely tunable SG-DBR laser. The SG-DBR laser has a 40 nm tuning range, ns tuning speeds and is 1.5 mm long. Typically the linewidth is in the MHz range due to carrier induced frequency fluctuations. We use an asymmetric Mach Zehnder integrated on the same PIC to monitor and convert the laser frequency fluctuations to amplitude fluctuations. This error signal is fed back through a stabilizing loop filter to the phase tuning section of the SG-DBR laser to reduce the laser linewidth. Through integration of all the optical components, the loop delay is minimized and loop bandwidths upwards of 600 MHz have been achieved. Using